For IWB, I like a holster with the loops or clips offset from the gun (e.g. Comp-Tac C.T.A.C., etc.). In leather, I'd look at the following:
Milt Sparks / Lou Alessi Watch Six:
Alessi Watch Six Dual Talon (Talon clips secure to the waistband, not the belt - very easy on and off, quite secure):
Fist-Inc #19 and #20 IWB:
Bulman PDC (nearly identical to Alessi WSDT):
Tucker Gunleather's The Answer IWB:
These are a few designs. I'm sure there are many more out there.
Milt Sparks / Lou Alessi Watch Six:
Alessi Watch Six Dual Talon (Talon clips secure to the waistband, not the belt - very easy on and off, quite secure):

Fist-Inc #19 and #20 IWB:


Bulman PDC (nearly identical to Alessi WSDT):

Tucker Gunleather's The Answer IWB:
These are a few designs. I'm sure there are many more out there.