I have a 4 channel that I use with my electric's that has the regular manual trims & I have a Futaba 7C with digital's that I use on my glow planes & I personally like the digitals a lot better.
with the digital I can program the sensitivity of the trim so that I can really tweak it in versus on my old one i always seem to need to be in between two of the clicks to get it right. I also like the fact that I never have to retrim my plane becuase you can't bump them out of whack.
Every flight on my electric is pretty much a trim flight because they're always off.

One disadvantage I could think of on the digitals is if you have to move the trim a lot. For example if you take off and your elevator is way out of whack then your bumping the digital for a while to get it where it needs to be where you could just slide the manual one way over.

It probably comes down to personal preference.

Hope this helps.