I own 3 Blacktips. They were an easy and affordable way for my wife and I to get into DPVs. We have upgraded ours to third-party 20ah batteries for better runtime. We keep a third one as a tow scooter or loan it out to friends. They are fine for 4000-5000ft cave dives (with upgraded batteries..) or tooling around wrecks and shore dives.
I owned a UV-18 many years ago briefly but rarely used it due to the weight (boat diving). The Blacktips have better performance than some old school tech scooters like UV-18/26, Gavins, or beefed up Makos.
However I'll be completely honest we have both outgrown the Blacktips. The 20ah batteries help and they have decent range but I do not believe the Blacktips to be very reliable scooters and Dive Extras quality control is pretty awful. Their customer service is so-so.
I still believe there is nothing comparable on the market in this price range but honestly I feel like we have all been unwilling beta testers for this platform.
Bad wiring/crimping for factory, numerous nose cone redesigns, handle redesign, poor quality potting and overheating ESCs, multiple firmware updates to address issues.
It seems they have mostly worked out the kinks now but these scooters do still overheat at higher gears after an extended period on the trigger. Most people will not notice this unless you're cave diving in high flow or racing someone with a better scooter.
Having said all that, the Blacktips is very DIY friendly. Most parts are easy to replace yourself if you are slightly mechanically minded. Dive Extras releases a full technical schematic and will sell you most parts. I give them a lot of credit for that.
They are not a bad scooter but if you have the money I would go with another brand.
I'll probably be upgrading to Seacraft or Genesis in the spring as I want something with external charging and no shaft seal.
For the reason of all the good things that you said, I still think the BlackTip is a great first scooter.
The investment is small (in DPV $$$ terms).
The BT is very capable. For people just doing wreck and reef diving, they may never "outgrow" a BlackTip. Especially a BT with a 20Ah battery pack. It goes plenty deep. and you don't generally need really long run-time on a wreck dive. But, if you are diving a CCR on reef dives, yeah, you might eventually, maybe, get to the point of wanting longer runtime (though, a 3 hour reef dive is a pretty long dive, and are you really going to be on the trigger the whole time? So maybe you could really do 4 or more hours?)
For when you first start out cave diving with a DPV, do you really need more run time than a BT w/custom battery gives? I mean, with just 2 x Dewalt 12s, it has a 3 mile range. That means 5280' of penetration, 5280 out, and the same left in reserve. Does someone new to cave DPV really need more than that?
And with a 20Ah pack, your Third is even further penetration.
It seems to me like a BT is great for a first cave DPV. And when you are ready to do more penetration than that, then the BT becomes a good tow scooter to have when you buy your Genesis (or whatever). I think very few cave divers ever go far enough in that a BT (used as a backup/tow scooter) would not be able to get them back out. Some do, but VERY few.
ANY scooter could break, so you always have to plan your dive to accommodate a DPV that dies. That's true whether you're using a BT or a Genesis.
So, when your DPV does die in a cave, well, it's an inconvenience, right? Not an emergency.
Which suggests to me that, unless a BlackTip is something that is going to die often, then it's probably reliable enough for the range it offers. Yeah? And, while I don't like the reliability of any PTB-based scooter, I don't think the BT is so unreliable that it isn't suitable for cave DPV dives in its range.
Now, I could be all wrong. I am trained for cave diving, but not cave DPV use, yet. So, maybe I'm just wrong.
This all seems a lot like what I tell people about lights. You don't need a big canister light as your first light. Good a good cordless. When you get to the point of needing a big can light, then that cordless light will be a great backup, which you will need to have anyway.