I could think up some issues, I mean for example strained or extra muscular fingers are not uncommon if using the DS phat, and you also need to have a strong lamp so that you can see the screen. Otherwise you can get trouble with your eyes.
Hardware-wise I'm pretty sure that the G6 lite works exactly the same on the fat one as on the slim I-did-not-eat-enough-porridge-during-my-childhood DS.