Very interesting!! Greg finally convinced me about a month ago to order a nylon hex drive block on RepairClinic, and I've been using the black bakelite Surgilator that Don S. sent me ages ago in the Frankenmore. While not as perfect cosmetically as Rick's, it is an EXCELLENT agitator and gets the job done! Jeans, towels, sheets, you name it, whatever I throw in there will effectively circulate! I prefer the "undulated" vanes of the Surgilator as they tend to Smackulate better and are more fun.
As for the Kenmore agitators...while I think the old Dual-Action is great, I wish Kenmore had an effective 1-piece agitator as well for their BD 18-pounders...why they didn't equip those with the Super Roto-Swirl is beyond me. I previously had one in the Frankenmore, and it's a good agitator (it can handle a large quilt/blanket with ease), but isn't too good with jeans. However, that damn Penta-Vane is the absolute worst 18 lb. agitator I've seen...what a JOKE. While the action will surprise you on small/medium loads, load it full with a high water level and there's hardly any turnover. Jeans, quilts, or blankets? Forget it...it can barely handle a full towel load! I only caught a few glimpses of a Penta-Swirl agitator in action, but with the curved vanes it might be better.
Regarding suds-lock--with the exception of the WO-65-2, I always have a bottle of fabric softener on hand when the load turns abnormally sudsy!! Oddly enough I haven't had any trouble with the Frankenmore, but the 1-18 and GE slow down considerably and take a good spray rinse (and even the deep rinse on some occasions) to clear all of the suds out. What's interesting is, the 2003 Dependable Care Maytag that I outfitted with a Power-Fin agitator NEVER suds-locks, even with all of that Mexican detergent on a small load. While it takes a spray rinse to get it pumping the suds out again, the tub always gets up to full spin speed.
--Austin