I have a LangPercussion with a 3 way tuning system. And, yes, you can tune the batter only, the reso only or both heads.....all from the batter side.
It would be nice to have the real deal but I don't think that's going to happen for me.....I'm satisfied with my Arnie Lang replica.
The only difference that I can see comparing Arnie's LangPercussion Gladstone hardware to the original is that Arnie does not 'groove' the three sockets on the drum key as Billy Gladstone did. Gladstone put the grooves on the key to identify which part of the key you wanted to use. He put 1 groove for the batter socket, 2 grooves for the resonant socket and 3 if you want to tune both heads. He did that so you could feel where the key went in low light situations. Pretty cool.
I too am sorry you missed out on the Gretsch Gladstone....it sound like it was a heck of a deal. But as you said...and I understand where you're coming from....it's hard to drop $350 on a drum you know nothing or very little about.