A few months ago I (finally) upgraded from XP/Sonar 5.0 to Win 7/Sonar X2.
No issues, hiccups or any other furballs.
I did a re-format/Win7 install and it went easier than I anticipated because I haven't done that process in several years.
On as side note I'm only running an AMD Sempron 2.8 gig with 2 gig of ram which is below recommended specs.
I did the free trial to test my system and I can record 4 tracks simultaneously (Delta 44) with a few effects for over an hour without problems.
No complaints here....hope that offers some valid perspective.
Have fun...carry on