I have the Suncoast single and it will hold close to 500 HP they say, but probably not towing 10K. There is a balance to be found in all of these upgrades. I know a few guys with the annoying problem of the truck not wanting to idle well because of the extra drag created by the triple. Or having to bear down on the brakes because the truck wants to creep at idle due to the triple adding to the fluid coupling effect. For me it came down to this, how much power are you going to have to hold and which one will do that. Sometimes more is not better. A single is less expensive by around $300 so if you don't need that much holding force then get a good single. My single has 40% more holding force than the stock convertor. Is that enough? for me it is.
Locked is locked whether single or triple, and the "mushy" feeling has to do with convertor efficiency and more important, stall speed, both of which can be specified to a certain extent when ordering.