I'm no expert, but I'd thnk sure you'd lose the speed benefit, might even be slower than you are now.
I assume that your OS is installed on the SSD. A fast SSD with the OS and JRiver installed on the same drive is the way to go.
Actually should be really easy... first backup your library. Then fresh install of MC (if you are like me and you have skins and custom resources, saved views etc., you'll need to copy those to the same directory names, probably the default one's on, the SSD).
The just restore the library backup. As your data is not being moved there shouldn't be any tweaking of your config to do.
You don't have to uninstall the other, you can test them if you want and remove the old install later. Just make sure you are not auto running from win startup the server from two different drives.