Yeah I feel your pain on the backlog, its just that this is so cheap for this system you will probably have to wait another 3 years until we see a $99 price drop on it so even if you want one game its worth getting for that price. Heck you could probably sell it used for more than what you paid new.
It doesn't make much sense to buy a DSi XL now at any price really, maybe for $25 or if you really want to have one in your collection especially if you can get the 3DS for $99.
I can testify that DS games look just fine on the regular 3DS and the black border around the top screen doesn't bother me at all. I have no idea how regular DS games look on the 3DS XL.