Speaking of having 32 and 64 bit sonar installed.
PITA to keep them both up to date with plugs.
Ever since I built my W7 64bit main DAW (except for a brief interlude where I uninstalled 32bit SONAR, bad call on my part) I've had bot 32 bit and 64bit SONAR installed. I've only had to go back to use 32bit once and that was to verify the settings in a 32bit only plug that I replaced in 64bit SONAR.
The next time I have to rebuild a DAW it's 64bit SONAR (and other DAWs I own) only and I'll install only (the very few) 32bit only plugs I own. IRCAM Trax, Drumagog, SamlpeVatiants(Tank/Moog/Tron/Philharmonic/Sonic Synth) & Acme BarGig's Headcase. One day these will all be 64bit I'm sure.
The following are unlikely to ever be 64bit AFAIK:
Vogengo Boogex, SoundToys Radiator, Empress Tremelo, Elevayta Space Boy, Bluenoise Rock and Metal Kits, Ferric TDS (free), mda Leslie (free) & nusofting DeepBoard (free).