Pioneer AVIC's are pretty good, they had the best features and although I'd be after an Audi look, I'm not after that "factory installed" look.
My only real issue with the AVIC was that it didn't have the features were important to me: proper DIS+steering wheel integration: so I could use the nav without taking my hands off the wheel or my line of sight lower than the dials, and on the odd occaision I wanted voice directions, I wanted to prompt for them without taking my hands off the wheel.
If any non-OEM unit allow that, then I might be interested in upgrading further, anything else is a downgrade for what I need - although technically possible to fit properly integrated MMI-style units, but mostly £2k-ish!
Not sure the "sub-par" comment is quite fair: The RNS-E was pretty advanced when it was designed (2003), but the 2G is an 8yr old design now, so hardly surprising that newer units have more feautres.... we bemoan things like lack of SDHC support, but in 2003 it wasn't exactly expected that people would want to put a couple of 32Gb SDHC cards into the units (SDHC was only standardised in 2006!).