I think I saw that add - and it certainly peaked my interest. I've already made my purchase, but I'm sure interested what a 3x12 for 600 would look like. Go take a look and let us all know.
Regarding english tin, I boiled on a 30"x5.5" english tin flue pan for the past few years and had absolutely no problem. When I got it, it had a few small leaks - but it soldered up nicely and never had another leak. A certain liquid flux and solder were recommended and it did the trick fine. Just make sure to clean the solder spot perfectly before begiing to solder.
Regarding lead - I'm gonna take a wild guess and say 75% of Traders are boilling on lead pans, including myself. Unless I was trying to produce organic sap, I'd be leaping on a decent 3x12 for $600.
Just West of Syracuse
3 x 10 Lightning
Sap Bros RO
600 taps and buying sap