I have a 21" 870 turkey barrel that takes Rem-chokes.
I'd be less concerned about the velocity loss than the lack of any choke. Our short barrels pattern just fine with the right tube in them. Some of the cylinder choked barrels I've used would probably not work well much beyond 15-20 yards.
Had a gunsmith take my 870 down to 21", rethread the barrel, it takes all the rem chokes. Has a mid barrel and end bead sights, plus I put a magnetic high viz sight on the end too. That gun has shot: turkey, geese, ducks, pheasant, quail, and doves. I rolled a turkey a number of years ago, with a 3" mag, 3 shot steel, out of a improved cylinder choke. At 30 yards that bird never even heard the the gun go 'boom' it was dead so fast.
The wads on the federal steel rounds I was using were so thick, it was almost like they 'cupped' the shot for just a moment longer and produced a tighter pattern out of that I/C choke.