If hardware ran X1 OK I can think of little reason why it wouldn't run X2 OK.
As you already have X2 64bit I'd suggest installing it and seeing what happens. The main 64-bit related crash-type issues I've found with a few years running 64bit Sonar (8 onwards) have been bitbridge related, especially regarding 3rd party plugins, so I'd suggest using 64bit plugs as far as possible.
As for memory, see what task manager and the Windows resource monitor tell you about RAM usage while Sonar is running. I ran X1 in 64bit (under Vista) in 4GB RAM Without any problems, but I don't use RAM-hungry soft synths or samplers.
If you do use plugins that hog RAM, then RAM 64bit, with it's ability to use more RAM, is likely to be worthwhile for that reason alone.