Tahoe / Denail Navigation Question

I was wondering what the difference was between the audio options in the Yukon / Tahoe. I am in the process of ordering (or doing a dealer locate?) and have plans of eventually adding an in dash computer / navigation such as:

http://www.azentek.com/webpages/atlas.html

I'd hate to buy the factory Nav system at $2,500 just to rip it out a few months later. However, if you get more than just the Nav system with the "UVB" option code, I'd consider it. (e.g. premium sound, etc)

So, does anyone know if there's a difference (besides the obvious Nav functionality) between the UVB and UVA option codes?

Thanks!