I've always wanted to see a side by side comparison for different slugging options:

1) Rifled barrel w/ Sabots
2) Smoothbore barrel w/ rifled slug
3) Smoothbore barrel w/ rifled choke w/Sabots
4) Smoothbore barrel w/ rifled choke w/rifled slug

Naturally, a person would have to have an exhaustive volume of ammunition brands and firearm brands/models, such that individual firearm or load performance wouldn't skew the data set. Which I suppose is why it hasn't been done.

I don't do much slugging, but I desperately wish I had a justification to own a Savage 212 for that purpose. I have a couple rifled barrels, but can't say the last time I used one.