The FS-10 is a must if you have a Blackstar amp. Personally, i had a lot of trouble using it. Could have been something i did, but i just could not exit some of the modes and thought there might be something wrong with the pedal. I think it may have turned out okay in the end but i put it back in the box and have not used it since, not used the amp much either so i can't say too much about it. If you are used to pedals like this you probably won't have any problems, but i'm not and i did.
3 modes means you can step through the banks, navigate all 128 amp patches & even edit & save effects without stopping playing. Tempo tap is really useful when playing live too.