The only difference between the mini Cougar and the 8040 Cougar is the grip. The grip is much shorter, and supposedly easier to conceal, but they also have the extended magazine with the finger grip which brings it right back to the same configuration.
I've tried both and settled on the regular 8040 Cougar with the 10 round magazine. I have average size hands and the mini Cougar didn't seem right in my hand so I would have bought the extended mag, at an extra cost. Didn't make much sense to me.
I do like mine in the 40S&W, and after I mastered the long smooth trigger pull it grouped really nice. Got a little blister on the bottom pad of my trigger finger, but that hold and pull gave me the best groups. Beretta, makes some of the finest defense handguns in the world and I don't think you'd be disappointed. RR