BD=King
The early DD machines didn't seem too bad, however, the current models are just plain flimsy! My DD Kenmore has been kicked out of the "laundry shed" and once I get the Dual-Action back in there it's going to be sold (or given away)!! I'd like to see how an early Design2000 or 24" DD Kenmore compares to what they have now.
The DD Surgilators aren't too bad (they're in Whirlpool machines that are a step up from BOL) and can handle a good-sized load. Somehow, the 27" machines with the larger tub seem to work better with this agitator. The lower-end machines are usually 24", and have a narrower tub than the 27" machines which makes it even harder for the agitator to turn over the load. Thus, the Dual-Action is absolutely necessary for these.
The belt-drive Super Roto-Swirl was another good agitator and worked well with the standard-capacity machines. I have one in my 1982 large-capacity Kenmore and it works great provided that it is not overloaded (2 sets of sheets is a bit of a stretch as I found out...maybe not with the Surgilator though). The water and clothes really move around with that thing...not so with a DD!!