There's a "new" track surface that's been popping up that might work VERY well for this purpose... Kyosho's Route 241 raceway uses it, and I think it's the same stuff that's used on all of the HTUSA tracks... and it's also what's used at the Underground Mini-z speedway in Korea (see video below), and THOSE cars look HOOKED up...
It's called Pytex carpet... it's the same stuff that is used in convention booths. The fibers don't com out and foul the drivetrains of the dnanos, it's smooth and has a very scale driving feel for Z's and 'nanos, you can AWD drift on it w/o flipping it over like RCP tracks, and I swear after running my dnano on it at 241, my car came off cleaner than it went on...
Someone (John at RCP... LOL) should look into it....it might be a viable option for Mini-Z and dNano alike
High grip Mod race:
http://www.youtube.com/watch?v=7-RAS2W6dHE
Dnano:
http://www.youtube.com/watch?v=vdUwukbaRCU
Drift:
http://www.youtube.com/watch?v=8cPcJMC0uLw
All on the same surface....