...I have the adapter that has the magnifying lens on it, can't play without it. Looks just ridiculous though, lol. It is called "super wide gear".
I've got one of those for my Game Gear, too. Yeah, makes a big difference in the playability. It doesn't fit properly with the adapter to play Master System carts; the spring clip hits the adapter. I can't remember if it cleared the TV tuner...
I never had a problem with it eating AAs, because I mostly used it in the car, plugged into the cigarette lighter, or at my Grandparents' place, plugged into the wall. If I did want to use it elsewhere, I had the (NiCd) external battery pack, too. It weighed a ton, and was kind of a pain clipping it to your belt and having the wire trailing up to the unit, but I seem to recall the battery life from it was fairly decent, at least until the cells started to crap out from age/cycles...