Valves aren't what they used to be. I heat sink the valves with extra rags...makes brazing a little tougher, but at least I don't cook any more cheap Chinese valves.
I'd hate to be the guy using a Turbo Torch these day...you have to use them full open and you can't adjust the flame size. Makes for any easy overheat situation.
I know few guys who can use a Turbo with out over heating line set and valves.