^No need for buyers regret, lock-up ain't that much more efficient. The quality of the converter is more important that if it's lock-up or not. Somewhere above 2800rpm, you have to start paying big money to get the best of both worlds. Those high stall, 4500+ that still cruise very nicely at 2500 or less, do so because you paid $800 for it, not $250. The fact you have a quality low stall, you'll never have to worry about slip or heat because the RPM just isn't there. It's a cruising converter, not a racer.
It comes down to maybe 200rpm difference, 1mpg, one less expense, and thing to go wrong.
Personally, when I swap in my 42RH, going lock-up because I can. That's about it. Hopefully I don't have to spend $1000+ to get a decent converter, otherwise, I'll probably be in your shoes.
