Experience with some 32bit plug-ins may not translate to others. I would strongly advise against using the 32bit versions of EZDrummer and Superior Drummer in 64bit SONAR. I would also suggest when running both 32bit and 64bit versions of SONAR it is a good idea to segregate the 32bit plug-ins into at least two locations: one for plug-ins which work well in 64bit hosts and one for 32bit use only.
In this particular installation since it is the first 64bit host install, adding the 32bit host back on the machine may ease the transition. Depending on where the 32bit Toontrack plug-ins were installed, it may be necessary to modify the default VST scan path in 32bit SONAR. Also consider adding the 64bit Toontrack software. Projects using Superior Drummer will probably run better in a 64bit host.