Here's a question:
For someone with an M2 fields version. Am I better served getting a tactical barrel and the receiver drilled and tapped for the iron sights, or picking up an M4 in the long run?
IMO the M2 even with a 21-24" barrel swings as well or better than many longer barreled shotguns, you could probably do everything pretty well with a Field in that length range instead of buying a second barrel that will cost a $1000.
The Field model with a 21-24" barrel with bead or vent rib mounted rifle sights is the favorite setup of the 3 gun crowd, in 21" guise its not all that much longer than the Tavtical model either.