First I did not take your comment personally. Please explain you comment on deco. Your computer does deco just like all computers do.
My support was based on ease of seeing and the intuitive menu logic. So intuitive you don't need a book to run it. And the large buttons so you can operate it with gloves on and the wide variety of batteries that can be put in it including the standard AA batteries from the grocery store. If ou cant find your way through the menues. then you don't have access to any of the functions of the computer, just like your computer. Let me ask you as you are not a frequent diver How long would it take you to change your computer from air to 32% gas on land.(not as a function of gong to deco gas). I have 3 aeris and I have to have a book to do it each time. which button combination and how long to hold each to get where you want. All I can use effectively is what is default for the screen at power up. I pitty people that have 4 button computers. Most divers only use 10% of their comuters at most. You are probably no different in that regard. The only thing that is overkill on the shearwater is RB support and that goes away when you are in rec mode.
I wanted a computer I could just wear around and not keep stored in a bag while traveling on a mixed dive/vacation holiday, something fairly compact. Anything that runs on an AA battery is, to me, bulky. And the shearwaters are very expensive; great, I'm sure, and I would not say no if someone wanted to give me one but it is a major consideration for me; the Petrel The dive shop had the Meridian on sale for under 300, so that worked out well, and (shallow, I know) I feel it looks nicer than a lot of similarly priced dive computers.
The meridian is functionally a simple 3 button computer - up/down to go through menu items, and a select button to change/activate selections. The fourth button is the backlight. I can very easily change my gas mix settings for nitrox on land, three button presses or so, no weird holding, no menu checking. Quick look at the dive log, ditto. I also use it as a backup alarm clock, watch and altimeter when traveling. It's a little hard to operate with gloves, but I rarely dive with gloves (I think 5-6 out of 80 dives) so that's also a bit of a non-issue. The display is large enough for me, and I have no problems getting the info I need with a quick glance, so the size is an overall win for me. The reason I mentioned the cosmiq was price and the fact it looks nice and simple for the smartphone generation; 2 buttons, nitrox, small, rechargeable, and it's less than half the cost of a Petrel 2.
So yes, actually my boyfriend and I will go through your replies one by one and decide together. 
