I once had both 32-bit and 64-bit version of S1 installed, and there was only 1 set of SoundSets; that has to mean that the SoundSets will work with either version. You can install the 64-bit version of S1 along side your 32-bit version, unless you don't have the disk space or just don't want to have the 32-bit version there and never use it. If that's the case, you can just make sure you install the 64-bit into a different folder, then you can just delete the 32-bit folder.
CAREFUL though! I installed my SoundSets to a completely different drive, so installing/uninstalling/deleting won't affect them. If you didn't do that, in other words, your SoundSets are in S1's installation folder, you can just copy them to a different location and copy them back after you install the 64-bit. It's roughly 35GB.
By the way, a 32-bit program won't crash JUST because it's installed on a 64-bit OS. Also, as the previous answer stated, the 64-bit version of S1 will only recognize 64-bit plugins. There's a program, called jbridge, that will 'wrap' 32-bit plugins in a 64-bit 'wrapper' so they work with the 64-bit S1.
If I were you, I'd contact PreSonus support directly and open a ticket to ask about the one set of SoundSets working with either version of S1.
