Hi everyone, this is my first post
Obviously a 7 string neck is wider and sometimes a little thicker & chunkier, so it should feel at least a little different to most people who play 6's, but that's dependent on so many factors.
Personally, I felt very comfortable with my Ibanez 7s since the beginning, it took me just an hour to get used to playing one, and churning out songs that I learned for the 6 string. My hands aren't very big by the way.
Every now and then I forget my 6 strings exist, but switching suddenly back to one feels very good, my fretting hand feels solid. So for me, playing a 7 means that I can play a 6 with ease, especially for playing material like Dream Theater songs.
But when I don't play my 7s for a while and I pick one up, again it takes me just a couple of hours to completely re-adjust and my hands to feel relaxed.
Playing heavy riffs on a 7 string feels **** good!!! Especially power chords, and it's not much harder than playing a 6 - try any Metallica tunes you know etc.
When playing on the high strings [g,b,e] especially playing the blues where bending is prominent, most people including myself tend to hook their thumb over the neck, so in this respect at first it may prove more difficult with the wider 7 string neck. Playing shred, especially wailing away on the high strings, probably won't feel so different.
My advice is to try it plugged into a Mesa Boogie 8) and not have any preconceptions about how it will feel. The low end that 7 strings have - not only due to the thicker string gauge, but also more wood being on the neck and body - will mean that powerchords sound chunky, rock out!!