Has anyone else noticed that there seems to be a pistol missing in the current M&P lineup?  Where is the G19/G23-sized pistol?  The 9mm/40 pistols go from full length grip down to subcompact with nothing in between.  While the subcompacts do come with an extended finger groove for the pinky, the backstrap just isn't long enough for me to get a good grip on.  There's a reason the G19/23 -sized pistols are so popular...I'm just surprised that S&W doesn't offer this.

Oddly, the only M&P pistol that feels the closest to the G19 size was the M&P45c (which feels fantastic btw), but I'm really itchin' for a 9mm/40sw at the moment.

M&P 45C is the G19 size.  Technically the fullsize 9 and .40 are smaller than the fullsize Glock frames but a smidge bigger than the mid-size.
But I see your point, I would not mind to see more of a mid-size framed gun or at least a fullsize with a grip reduction.

Get a SD9 or SD40, it is almost the exact same size

The M&Pc & G19 are closer in size than one would think. This picture shows a M&P9c w/ a pinky extension mag on top of a G19.

While that may be, that slight .5" difference in the length of the backstrap makes all the difference in the world.  I can hold on to a G19 and M&P45c quite nicely, or any other gun approx 5" or greater in heigth, but the M&P9/40c's backstrap just doesn't seem long enough.

As much as I wish they would make a 9/40 the size of the M&P45c, it is unlikely to ever happen. The compact 9/40 already fulfill the concealed carry role, while the full size covers open carry (and can be reasonably concealed). It doesn't make sense for S&W to make a mid-size. Although it also didn't make too much sense to make the SD, especially since the M&P has taken a price cut across the board.

I compared my new M&P 40 to my 1911 Kimber Tac pro and it pretty much the same size its actually shorter a air longer and about 1/8 thicker but its 15+1 Versus 8+1 so naturally I went to the M&P. when I bought it just yesterday, I laid it on top of a glock 23 and it was just a litttle bit bigger but smaller than a full size glock . its more compact than full size to me anyway.

That's why I bought the 40c and picked up a couple 15rnd magazines with x-grips. I use the 15 rounders at the ranger since they are so comfortable and I carry with the 10rnd finger groove mag. This helps me out a lot since I am so small and the longer grip makes it very difficult to conceal. Best of both worlds!!