I've used a CTAC daily for over two years. Keep an eye on the screws that hold the belt clips on, one of mine likes to loosen up every week or two. The kydex does take a little getting used to but after a week or three stopped bothering me (I started carrying with leather holsters).
The only way to easily spot a CTAC (or most other tuckable holsters) is to look for the clips over the belt. This can be minimized by having the belt the same color as the clips. Now, it the person is using one of the alternate styles of clip this becomes more difficult to impossible (think the velcro clips). Just something to keep in mind if you chose to carry somewhere there will be gun savy types who would frown on you carrying there.
A general comment as far a comfort and wearablity, in the summer of 2005 I helped my father move. That wonderful experience was over 15 hours. Not only did the holster not cause any issues I think it saved me from a nasty bruise on my hip (gun/holster took the hit, not me). Dad didn't think I could carry all day but it wasn't a problem. His girlfriend (at the time) was our only help and she never knew that I was carrying.