Obviously, to assume a uniform correlation between size and quality, or cost and quality for that matter, is not appropriate. There will always be some exceptions.
That said, overall it will cost more to make something sound better. It will cost more to make something smaller. Ergo, for the same price, one can ON AVERAGE buy something that sounds better, if compromises did not also have to be made to make it smaller.
As to the 943s on plug in power, depending on the music you will be recording, and the voltage of plug in power provided, distortion from too-high SPLs may be a concern.
Personally I can hear a distinct jump in quality between AT853s* and a Studio Projects LSD2. Obviously, the At853s are handy due to their small size, and sometimes the LSD2 is just too big. Sometimes I will run the AT853s openly right next to the LSD2. Differences are always clearly audible, though not night and day, and I always prefer the LSD2.
So my suggestion to you...if you want the best quality, invest in better mics to run with the FR2LE instead. If you discover you must run stealth with a smaller recorder, for about $10 you can get a 4.7K style mod (maybe talk to Chris Church for the best value resistor to use for your particular setup) done to your AT853s. In theory you might get 1-2 dB extra noise. You will not be able to hear that over the ambient/crowd room noise on a stealth recording.
*(regardless of how they are powered, I ran mine off a 3 wire battery box [which is identical, from the mics' perspective, to the phantom adapters you use] for a while and switched to 4.7K mod for convenience with no audible drop in quality)
edits for formatting
Edit 2: As to laziness/point-and-shoot, I don't think I've ever suffered from that. Certainly for a show I really care about, my best equipment always comes along. But there are shows where I only bring the mini-rig. Honestly, I think those are shows I wouldn't have bothered to tape otherwise, or I wasn't confident that I could bring open gear in, didn't want to do all the legwork to clear things in advance, etc. But maybe I'm just in denial.