Have two carry weapons. Started with the Springfield XDm 9C and then added an S&W M&P Shield 9mm.
The XDm weighs 33.2 oz. with the 13rd magazine and one in the chamber while the Shield weighs 24.9 oz with the 8rd mag and one in the chamber. The 7rd mag reduces the weight be about 0.7 oz.
Both are carried in CrossBreed type IWB holsters and I can conceal either one without a problem. The 18 rd mag in the XDm is a bit more of a challenge to conceal, however.
The additional 8.3 oz of the XDm is definitely noticeable and for that reason I prefer the Shield for carry, but for now I shoot much better with the XDm. Need more time on the range with the Shield to really get a handle on it.
When carrying the XDm, I have to take in one more notch on the belt to keep things up where they are supposed to be - the bulging eyes might be a bit of a giveaway that I am carrying! [I find that using Perry suspenders with the XDm, when that is possible, greatly helps with the comfort level.]
Of course there is a significant difference in the number of rounds that you have to work with but I figure that if I need more than 8 bullets I am probably toast anyway.
For what it's worth . . .