Ratio Deco builds on standard gasses.
If one doesn't know what specific depth one is going to, I can use the that framework to prepare for a sequence of dives in the exploration domain, which would in some cases make an "optimal" gas and deco approach difficult (how do you mix the "perfect" gas for a dive that you don't know the depth of yet?), but rather build the dives on gas logistics, Ratio Deco and maximal operative depth, in a manner proactive rather than reactive in-water.
Don't you select your Standard Gases based on a target depth, where there is a list of depth ranges? So, you choose your SG based on the depth you are planning to dive to, by consulting a table of gases?
How is that better? You have, say, 5 gases to choose from for all possible depths. With a Best Mix approach, you have a huge number of gases to choose from, including all the same mixes that are in your list of SG. Let's say (hypothetically) that you have a standard gas for the range of 30m(100fsw) to 45m(150fsw). And a different gas for the range of 45m(150fsw) to 60m(200fsw).
Now suppose you're going to do a dive and you're not sure what the bottom will be, but you are pretty sure it's around 45m +/- 5m. With SG, you have to either choose a gas that is so rich that you could end up not being able to go as deep as you want, OR you have to choose a gas that is very lean and results in excessive deco. With a Best Mix approach, you could select a gas that would be just right for 50m - so you could be assured of going as deep as you might want, but it is not so lean that if you end up only going to 40m, the gas results in unduly long deco.
When you are planning where you don't know a specific depth, it seems like the Best Mix approach is significantly better than the Standard Gas approach. After all, if you plan using Best Mix, you CAN still choose the same mix as you would in a Standard Gas approach - if it really is the best mix for the dive you're planning. But, you are also free to choose something else if it would be better for your particular scenario.
I haven't had the formal training on SG and RD, but to an outsider, it SEEMS like the only real justification for standard gases is that you have learned to plan your dive using RD and RD depends on them. I.e. the tool you are using forces you to accept limitations on the gases you can use. All the other "reasons" I've ever seen or heard just seem to be rationalizations piled on top of that.
Ease of blending? Hey, if you're in a situation where ease of blending makes a certain gas preferable, the Best Mix approach will totally accommodate you choosing your gas based on that - it just wont' require you to choose that gas. Personally, I have never done a dive where that made one ounce of difference. When the gas I want isn't what is banked at the fill station I'm at, I request a custom blend and it doesn't make it any harder or more expensive for me whether I choose a custom blend that is a standard gas or a custom blend that is my own requested concoction. However, I can see where it could be a valid concern if you're taking some big bottles, a whip, and doing your own fills on site. Then, like I said, you can choose to use a mix that is the same as a standard gas if you want to. So, Best Mix doesn't have any disadvantage there.
Personally, if I travel to a different country or continent, and meet a person I want to go diving with, and we don't speak any of the same languages, which happens, that's seamlessly facilitated as well, in terms of decompression. There's no way to quantify such utility with doppler technology.
Huh? "no way to quantify such utility with doppler technology" What does that even mean?
As far as traveling to a different country and diving with someone that speaks a different language, how is RD better, or even as good as, agreeing on using Buhlmann and the same Gradient Factors? I could speak exactly zero of another diver's language, but I could show them my Perdix, what algorithm it's set for, the GF it's set for, and they could show me theirs matches, and we could dive without having to converse at all.
People are fond of saying RD is not an algorithm, it's a strategy. So, which sounds easier to you - planning a dive with someone who doesn't speak your language where you have agreed on a deco strategy? Or planning a dive with someone who doesn't speak your language where you have actually agreed on a specific algorithm and parameters?
To be sure, Ratio Deco doesn't numerically factor in, say, fatigue, hydration, exertion, temperature, nor do the alternatives, to my knowledge. But it does certainly build a familiarity and readiness towards adaptation, which may or may not be helpful in some circumstances.
RD is unique in that? Diving using Buhlmann and GF somehow precludes the diver from building familiarity with their personal deco and what they may choose to do when they are fatigued or feel less well-hydrated, or whatever?
I feel like having a measured, repeatable, accurate and precise baseline to work from is better than an on-the-fly mental calculation. My computer will give me a different baseline to use my judgment against if I dive to 90' for 15 mins, then go to 130' for 15 mins, versus if I start at 130' for 15 mins then go to 90' for 15 mins. Either of which I would rather work from, as a baseline, than starting with the info that I have been down for 30 mins and my average depth is 110'.
There's of course the cost factor, which naturally shouldn't dictate our choices, but in fairness, my 330 has cost me less than $1 per month in use towards computer and software, training cost aside (I omit that cost as I assume it would be a factor near enough constant across solutions/agencies, and even if it isn't, Ratio Deco surely wouldn't be the only factor differing across them).
Cost? You choose to use a deco method that seems to be quite clearly one that produces longer, slower ascents than commonly accepted modern, computer-based ascents produce. How much extra helium are you using and how do you factor that into your cost analysis?
Further, I don't depend on external hardware
You don't use a depth gauge? Perhaps you meant that you only use mechanical depth gauges and mechanical timing devices? Because if you are using an electronic device to tell you your depth, your time, and maybe even your average depth, then your statement may possibly be a Kool-Aid-induced hallucination?
When you talk about your "330", do you mean a Uwatec/ScubaPro bottom timer? They don't give those things away. When you factor in the extra cost of the gas required for the longer, slower ascents you get from RD, how long do you really think it would take to have saved enough to pay for the difference in price to a proper tech computer?
And, are you using the 330 to tell you your average depth, or are you tracking it in your head (but still assuming that the 330 is accurate on your depth and run time)?