520/530/720/730 all much the same once you stick your own navcore on there. You'll notice the speed difference (over the One XL) when searching for a destination and the navigation screen updates quicker too - no more missing the exit from a roundabout because the tomtom's lagging behind.

I prefer the 9.170 navcore, even for my 720. No spoken street names, voice recognition or bluetooth, but that's all gimmicks anyway. Nice simple menu structure and you can turn off Remaining Time/Arrival time (always bollox anyway) to get rid of the clutter.