Health issues have made me lot more sensitive to recoil, but gf's 20 gauge 11-87 with 3" No 2 buckshot is more comfortable to shoot than my 12 gauge 11-87 with any standard 9 pellet OO buck or 16 pellet No 1 buck I've tried. Haven't got a vent rib barrel yet so don't trust low recoil buck in it, it cycles low recoil buckshot and they are real light in recoil but it cycles very sluggishly with factory slug barrel and low recoil buck so I don't trust it.
Honestly with her 20 gauge 11-87 we can't tell difference in recoil between 2.75" No 3 buck loads and 3" No 2 buck loads, we've loaded gun for each other with mix of the sells and can't tell them apart by feel YMMV and I'm sure a pump or double would feel the difference.
All the regular Foster Slugs feel the same to each other, I've got a box or two of the 1 oz Brenneke for her 20 gauge but haven't got around to trying those yet.