If you like revving, you will probably like it, moreso if you spend a lot of time over 5K
If you like taking a 2 week trip, with a vetter, 2up, & lots of gear..you probably wont like it.
If you are likely to gtab a handleful of R's, and are not afraid to dump/sliiiipppp the clutch, its probably for you.
If racing off the line and you bog, you can get revs back quicker.
I would not run my 836 without one.
I have also NO rotor, that is a bit different animal.