http://nanoloop.com/advance/versions.html
What's New
The current version 2.5 is a minor update to its predecessor 2.3. Functions, design and file format are the same, except for the following differences:
- More accurate nanolooop-to-nanoloop sync
- "Load on first beat" option for loading patterns
- Preview load in song editor also loads empty patterns
- Pattern length in song not fixed to 16 steps
- Song can start immediately or in sync with current pattern2.5 carts contain a new flash chip. The 2.5 software is compatible with the new chip and the old one, so it can be installed on 2.2 / 2.3 carts, too.
I've also found that when you press select when it starts up instead of doing just a greyscale version, it inverts whites and blacks, but keeps the pink of the squares.
There's also an update rom so if you have a GBA flash cart you can load the update rom on there and then just use that like you would in the cart to cart update process described on the page. I tried it and it works perfectly.