I shoot and reload the 357 sig. Not because I feel it is better then any other round. Just ended up being what I chose. I do have 9s, 40s, and 45s. Do reload for .45, being a 1911 fan as well.
I do not understand the concern of .001 to .003 difference in size compared to the 357 mag? I am doubting anything shot will know the difference. It is close enough where I have read some who load their 357 sig brass with 357 projectiles. Claiming less problems with set back.
The sig feels to me to have the snap of a 40 and the push of a 45. Could just be my imagination. And I am different than the average guy. Never owned a Glock, and like small primer 45 cases.