The only thing to really watch for is the age / revision of your installed CAN Gateway module. This module controls all of the computer modules in the Car that use the CAN network system (including the RNS-510). If you have (or know someone with) VCDS, then post up the Revision of the Module and the helpful chaps on this forum will let you know.
If your Revision is too old (I believe Rev L or older) then the Can Gateway doesn't properly communicate with the RNS and do a full switch off, meaning a trickle current will always be present at the RNS and it will never "truely" shut down. Over the course of a day or so if not used, it will flatten your battery.
Options are either stick to a Rev A or B unit running a firmware no later than 1100 (as I have) or update the Can Gateway for a newer version (about £100 from fleabay) and get any version of RNS-510 you like including the latest (and best) "C" Rev models with the LED screens.
Whilst the older firmware models (like mine) do work brilliantly, you do loose a few features that running a more modern firmware will give you.
Support for SDHC Cards (over the original 2gb limit)
Road speeds displayed on screen
On screen Clock when the unit is off
Faster operation
Support for Rear Camera and OPS
Support for Voice Activation
Hope this helps.
ps. MortyGTDI (darren), Steve P and VRSCarl, amongst many others, seem to be the best boys to ask !
