I have fired a good many slugs through several rifled choke tubes. Brenneke, Truball, Lee, Lyman Foster and sabot, SST, Lightfield, BRI and some run of the mill factory Fosters.
For me, bottom line, the foster slugs did no better, no worse than through a plain barrel. Lee key drives a small improvement, maybe an inch reduction at fifty yards. The expensive sabot slugs were marginally better than from a cylinder bore.
For my money, if I had a smoothie I'd stick to the Federal Truball, which also shoot well out of my fully rifled barrels. The Fosters, for me, have done the best out of a smoothbore with i.c. or mod. Choke.
Guns used, 1100, 870, 37, 695k, 210 212, 220. Rifled tubes from Rem, Hastings and Browning. I had a five inch Hastings tube I had high hopes for and it was only o.k.
Rifled barrels, Remington, Savage, Hastings.
Slug barrels, smooth, Rem, WW, Savage, Ithaca original Deerslayer which shot cheap fosters better than any other I have tried.
As always, these are my experiences. Your results may vary.
I learned long ago that for me fifteen to twenty slugs from the bench was a full day. Now that I've had back surgery and am well into my seventies, that is a little much.
200 birds at trap isnt a problem. Experiment but dont develop a flinch.