I'd recommend installing FLPro on the SSD for faster loading. Since SSD wear + tear is only impacted on SSD writes you only need to worry about FLPro writing to the disk, which only happens in the AppData folder (by default).
If you have your AppData pointing to the SSD you might want to consider re-locating the log file (Configuration->Advanced->Folder settings) to the HDD just to avoid unnecessary writes to the SSD.
One last thing... FLPro searches on SSD based data are blindingly fast so if you have some static data you need to search regularly you might want to consider moving it to the SSD.