I have several for different firearms and they work well for me. They are a must have for me because in good weather I will be on my bike wearing a T-shirt and without the "tuckable" the wind would keep my shirt up and handgun exposed. Jim.
My suggestion would be an Alien Gear Tuck 2.0 or their newer 3.0. I use a 2.0 now and that is one extremely comfortable piece of equipment when carrying my Sig 320 compact. Just ordered the 3.0 for my XD Mod 2.
I've had excellent results (as in people who knew I was carrying couldn't see the outline of the gun) with a Comp-Tac CTAC and Alien Gear Cloak Tuck 2.0 holsters. I have a Henry holster that is tuckable, but I have not yet used it "tucked."
+1 for the Crossbreed super tuck. I have several of them and they are, in my opinion, the most comfortable holster on the market. I tried the comp-tac and the alien and they did not feel or fit me near as well as the crossbreed.
I have had several LEO's recommend "Remora" holsters for the tuckable versions. Anyone else have any luck or comments/reviews regarding the remoras? All opinions i have heard to date have been GLOWING, and wouldnt have any other holster type of comments
In my experience, if the shirt is long enough and is bloused, you shouldn't have any trouble. There is no tugging or stress put onto the part of the shirt that is tucked in so it is VERY unlikely that it will become "untucked". The blousing allows you to move pretty freely without any issues.
I do HIGHLY recommend you practice with an unloaded gun (check, and double-check) that you can get your gun out in a hurry. It can be a lot of shirt to pull and may require a firm grip of the shirt material and a lot of pulling up to expose the gun. Also, if an undershirt is worn, this dramatically complicates things because of the likelihood of both shirts being grabbed and the gun being sandwiched between them. Not a good thing at all.
Like all things, a little bit of forethought and a lot of practice will expose any issues and give you the highest chance of success. Good luck.