The barrel length really has little to do with printing, unless you start carrying firearms with 6"+ barrels. At that point, the barrel will likely print and people may start asking you questions about your anatomy. Seriously though, printing is caused by the grip of a gun. The longer the grip, the easier it sticks out underneath your clothing.
The Springfield XD® Mod.2™ has the GripZone® and a 3" or a 4" barrel. The Springfield XD(M)® has no GripZone® and a 3.8", 4.5" or 5.25" barrel. I assume that you are looking at the Springfield XD® Mod.2™. The 3" version is called the sub-compact model with a height of 4.75" (Compact Magazine) or 5.5" (X-Tension™ Magazine). The 4" version is called the service model with a height of 5.5". The 3" version is more concealable with the Compact Magazine than the 4" version. Having said that, it is certainly not difficult to conceal the 4" version as many other firearms have the same or similar height and are being carried concealed every day, such as Glocks, Sigs and 1911s.
Do not worry so much about printing. Many people would not even notice an openly carried firearm. Only other concealed carriers may notice your concealed firearm.
Galco makes quality holsters, including the KingTuk™ tuckable IWB holster. If you like this style of hybrid holster, then check out the
Alien Gear Holsters' Cloak Tuck 3.0 IWB holster. It is significantly less expensive.
Note that I don't carry any of this. I don't carry handguns with a grip safety, as it is an unneeded feature that only gets in the way of the operator. I usually carry a Glock 19. I don't carry hybrid holsters anymore as I find the
NSR Tactical LLC-4 much more comfortable.