Here's my take on jBridge, and I've used it a lot, almost 100% until most of my go-to plug-ins went 64 bit.
1. You don't have to uninstall Bit Bridge
2. It will allow you to use some 64 bit plug-ins inside a 32 bit host program, but I would stick with SONAR 64.
3. You will have to go into SONAR's plug-in manager and manually tell which plug-ins to load with jBridge...this can take some time depending on how many 32 bit vsts you have.
4. In previous versions of SONAR sometimes certain plug-ins had graphics issues, this seems to have been cleaned-up quite nicely with X3 and shouldn't be a problem.
5. jBridge plug-ins, unlike those using Bit Bridge do not "Sit on Top", they behave as your native 64 bit ones do and you can use the normal vst meneus with them.
6. It works fine with both synths and regular effects.
7. It's a dirt cheap alternative to Bit Bridge that works quite well (Plus there's a demo), better for the most part than Bit Bridge....what are you waiting for?