Hm, I'm going to bump this sorta old topic to say that I've chronoed some slugs through a Mossberg 500 Serbu. In an 18.5" barrel, standard Remington 1 oz. slugs were doing 1410 fps. Through the Super-Shorty, 1140 fps. That's less than a 20% velocity loss. Reduced recoil was, coincidentally, 1140 fps through the 18.5" and 920 fps through the Serbu, once again less than 20% loss. It wasn't my chrono, though, so I only shot slugs through it.
As for practicality, reduced recoil slugs and buck kick about as much as a stiff .44 magnum load, which is easily controllable in a 4.5 pound gun with a VFG. Even one-handed, my face isn't in any danger. Actually, if you do the math, 432 gr (54 gr * 8 pellets) at 920 fps (I'm assuming the same velo as reduced recoil slugs) has the exact same recoil as 300 gr at 1325 fps, identical to Buffalo Bore .44 mag. Patterns aren't that bad either; all the pellets stay well within a standard size silhouette target at 10 yards, I'd guesstimate an 8"-10" spread (other brands might pattern tighter). Even at 920 fps, 8 pellets of 00 wouldn't exactly tickle.
The reader is free to draw their own conclusion from the above data...
Personally, I prefer an intermediate caliber rifle over any shotgun for home defense, though.