I'm not a hardware kind of guy, although I do find these matters incredibly interesting. I'll chip in my two cents regardless.
I would be willing to spring for a GP3X provided it won't cost more than $250, and that's pushing the roof a bit. I'd prefer $200, and I think that would be a very reasonable price. Any higher than that, I'll save up some more and buy a UMPC, which in a couple of years will hopefully be vastly improved all around.
Its screen diagonal should measure anything between 3.5 and 4.0 inches, with a resolution of 320 * 240. I love the current GP2X screen, an improvement on it would perhaps be the ability to show more colours on-screen at a time, which would reduce colour banding. The backlight should be user-adjustable, preferably with a hardware slider switch.
Speaking of a hardware slider switch, sound volume should be controlled by one. I'm not very happy with the software implementation that is present in the GP2X, and this simply cannot work well on a handheld where firmware may be overridden and where there is no guarantee of a specific standard use of buttons.
The batteries should be a flexible issue. There should be Li-ion packs available that would fit in the same slot as rechargeable AAs. That would be a win-win situation, no doubt. The Li-ion would recharge via electrical adapter, but be modular and replaceable with both other GP3X Li-ion packs or with a certain number of AAs. The number of AAs should be anywhere between 2 and 4, but not more than 4. With some creative use of space, they could get away with putting 4 of them in there, that's not something to worry about. Of course, two would be best, but if by using 4 I would be guaranteed 6+ hours of life at normal, non-scaled back usage, I would happily go for it.
The GP2X control layout is ideal all around. I wouldn't trade it for anything else. The stick should be of course replaced with a DPad (any kind of DPad that works well for quick reflexes, any patent can be avoided with creative design).
What's under the hood seems to be the focus of the debate here though. A lot has been accomplished with a single 200Mhz ARM cpu. There's no need for dual core. Just one 266Mhz ARM with solid Blitting acceleration, preferably with alpha-blending support. If it would have this, the sky would be the limit of what kind of games could be done on it. Keeping things simple and not over-powered will also take less toll on battery life. I wouldn't want to have to recharge or change batteries every 1 or 2 hours of use, that would plain suck.
The external design of the GP2X is also something that I am incredibly fond of. It's simple, modern, sharp, and unpretentious. It's very functional (with its headphone jack on the top as it may be, JaqMs) and it is comfortable for my hands. I wouldn't change anything about it really. I only hope they won't go for an all-glossy casing, other than that I trust GPH to make a sensible design choice if they will need to.
What if the GP3X was to have 2 SD slots? That would be the tops. Once we could use for storage, and the other for an SD peripheral such as WiFi or TV tuner (or more storage if we so desired). That would really take things to the next level - I know that the Zodiac did it first, but it's a great idea that should be used. Built-in WiFi would be overkill as it would increase the unit cost for sure, even if only by $10 (remember, the lower the price the more people will buy it, ie. I will buy it
).
Better battery monitoring would also be a step up, although I'm sure the GP2X firmware will be capable of accomplishing this in the visible future.
I suppose this is all that I can think of on the spot. I'll close by saying that I hope the GP3X won't be launched before mid-2009, and that the GP2X will maintain (and gain) community support along the way. Not even a year passed since the release of the MK2, and as you can see the homebrew scene is just getting fired up. More and more great original releases pop in every month
- Alex