If your effects are working for you, there is no great reason to change. If they are incompatible or unstable, you will know it soon enough. Versions that are native 64-bit could possibly be written to work more efficiently (if you have sufficient memory installed), but may not be so in every case. If you are investing in a new plug, then you are more likely to be able to keep it in new versions of Sonar etc. if it is native 64. The history of computing is that newer versions eventually replace older versions, if not because they offer better features, then because they are rendered incompatible by developers who cannot afford to support old stuff that is not making them any new sales.