I read somewhere that the glock .380 is too big and has a horrendous trigger pull. Personally, I gave my shield 9 to my son. It don't fit in my pocket. My bodyguard.380 does and is my constant companion. If you are of slender build, you can use a lot of iwb holsters. If you are overweight and have a hard time keeping your pants up, then most iwb holsters are too uncomfortable (at least in my case). As for a shield .45, I would think that the m&p .45c is probably the better choice. Of course that is just my opinion, which everybody knows about opinions.