I will talk with hardware devs about changing the lcd screen to a 640x480 or 800x600.
640x480 might be OK. But 800x600 or 800x480 is a definite NO.
But anyway,
if having a bigger screen resolution decreases performance, i would stay with a 320x240 screen. Remember that the "bad" thing about Dingoo and Caanoo is that they haven't got enough power for emulating some consoles fullspeed, and if you want full screen gaming, there is always a big FPS drop because of scaling.
What i expect from GCW is a fullspeed SNES emulation. Don't ruin it by putting a large screen, and then not having enough CPU power to emulate + scale.
Also, a 640x480 screen would eat the battery 4 times as much as a 320x240 one. Also, higher res screen = higher price.