I like the idea of a tub of Evap-o-Rust with a pump and a shower head spraying it all over the offending part, then recycling it to spray over the part(s) again and again.
Relatively cheap, only a bit of a hassle to set up, and removes rust down to good metal until you get to parts that don't have good metal anymore. But at least then you know where the rust stops.
Seems like it would work really well for most big parts (like fenders, tubs, frames, etc) where just dropping it into a bucket would work for small parts.
I use it extensively and it has worked pretty darn well for me so far.
I tried taking the rust off of a 100 year old or so railroad tie, and the tie just laughed at the rust-remover. It did take some off, but the pits were so deep you'd swear there wasn't going to be much metal left under there.
But every "normal" I've used it on came out pristine. Or mostly pristine.
Just takes time and takes up space for larger setups. So not for use in a busy work area.
Paul