That's a tough one - I've never been able to try a holster for fit and comfort before I bought it, and thus have a whole drawer full of leather/kydex that fits my piece fine but doesn't fit me for one reason or another. What I've done a couple of times and it works best for me is that I found a local guy, retired copper, who does pretty good leather work, and he spent some time working up exactly what I was looking for. Only charged me about 60% of a mass-produced model, too.
I don't have a holster for my EMP4 yet but 4" barrels aren't real common. You'll see more 5" and 3.5", which will probably work okay, but they are't going to be a perfect, molded fit. I'm not huge on Kydex, which is totally gun-specific and if you go Kydex you will probably need to do some heating and molding in your wife's oven (heh, heh). A lot of companies market their holsters by make and model of handgun, manufactured from a dummy pistol, and the EMP4 is new enough to the market that they haven't caught up.
If you're okay with OWB, you've got no problem - I'd use the Yaqui Slide from any number of makers, Brownell's or Midway or probably even Bass Pro/Cabella's/Gander Mtn. Barrel length is no issue and most all have a tension screw for the slimmer frame. If you want inside the belt or IWB, you might have to run down a custom job.