Lots of ways to sharpen. Since I do batches of chains at a time, I take them off the saw (or receive them that way), and need to do this for my cleaning method, inspection, repair, etc., anyway:Seems like a waste of time taking the chain off and putting it back on, then having to do it again to be the right way.
While I normally use a grinder, I have also used spare / scrap bars held in a vise with a Granberg style filing jig, or a filing vise:
But the flipping of the saw in the vise does not require removal of the chain from the bar. Just make sure that your powerhead does not leak, and flip the whole thing over. A lot of guys will do this in the woods too, using a stump vise, holding it up to their chest like a sting bass, etc. Eliminates (or reduces) some of the right-hand / left-hand filing problems that some folks have.
Everyone has to find something that works for them!