I have upgraded my system in 3 steps
1. 861v6/ID40 to 861v8/ID41
2. 7200HC to 7200.2HC
3. 7200 to 7200.2
My experience is that every upgrade was a big improvement. I can't say that any of the upgrade was better than the other. I think you will be pleased with any of the upgrade.

861v8+ID41, HD621, G98, Arcam P35, DSP7200SE, DSP7200HC, SW1600, DSP320.
2xMS600, 2xMS200, 2xDSP3200, AC200, Explorer2, 2x218, AD88, Prime, 251, 210