I had a similar dilemma and was faced with either initially going from NDS (with a PS555DR I also owned) to ND555, or going from 252/SuperCapDR to 552 (non DR), keeping my 250DR.
I demoed both options at the dealer (in a similar system to mine) and then took my preference home to try in my own system, and many thanks to James at Tom Tom for indulging me.
The result: 552 first, followed by a ND555 a few months later. Buying both pre-loved/ex-dem minimised the gap between the two purchases.
If you like, I could swap my 250DR for your 500DR so you could try this out. No rush to swap back and no need to thank me.