Well it ultimately depends on
which Galco and Desantis holsters you are using, and which guns are being carried.
For IWB carry if makes a BIG difference IMHO. The IWBs from Rosen, Sparks etc.etc. carry much flatter and more well balanced than say a Galco Royal Guard or Desantis Cozy Partner. For IWB it's all about the loop placement.
On the above mentioned Galco and DeSantis rigs, the loops are right on the gun and close togeather, this adds thickness and doesn't support the holster as well as an IWB with the loops out further from the portion of the holster carrying the gun, spacing the loops out further makes the rig more stable, which also leads to being more comfortable as the weight is better distributed along the waistline and the belt.
For OWB, I don't see much over all difference, I love my Galco Avenger OWB just as much as my Milt Sparks VMII.
I don't know whay major non-custom makers like Galco and Desantis do not make a more well thought out IWB.
