I use a DS Lite too, and I love it. The sound is perfect, it has two backlit (frontlit, no idea..) screens and despite it's size it's still portable. Mine after 4 years of heavy use still has awesome batterylife. And the best part about Nanoloop 2.5 is that you actually only need one cart to make seamless mixes!
The only annoying thing about using a DS Lite with Nanoloop 2.5, is the cart sticking out.
But yeah, I'd say go for the DS Lite.
Offtopic: so that means you'll start writing some awesome Dubtunes on Nanoloop 2?
no dub tunes right now, but definitely something that I'm liking. I'll share soon!