I have carried a Glock 19 AIWB for several years now. Quite comfortable with a proper holster. I recently started carrying my G17 with an RMR fairly often, also AIWB. I carry literally every waking hour, and my job requires lots of bending, reaching and some physical labor. The key is a well designed holster that fits your body style. As I type this, I’m sitting in my recliner wearing my G19 in a Keeper Lite from Keeper’s Concealment. As usual, I’ve been wearing it since I first got dressed this morning. Spencer Keeper makes an excellent line of AIWB holsters, and also teaches classes on appendix carry.I absolutely don't think a Glock 17 is something I would want to carry in an AIWB position. Seems to me like it would really make lots of normal movement almost impossible, not to say uncomfortable at the least. Glock 19 might be a little better but still not what I would want to carry that way.
When I carry the G17, I use a holster from JM Custom Kydex - another company that makes a very good line of AIWB holsters.