this Gretsch Jet double neck Baritone is on my list of must have - at least of must play (not a fan of the sparkle finish)! A Baritone double-neck is something - more interesting to me than a 6/12. I would open-tune the regular neck for slide so I could play it from upward and shift super quick from one neck to the other.
Two Bigsbys are a lot but I'd probably enjoy them if I was better at using them!
It's hard to comment more on a Gretsch guitar since I assume that they are perfect and that you just have to write Gretsch.
Danelectro also produced a baritone double-neck - I don't know other brands that did it.
While researching this guitar, I discovered that Gretsch also releases its own line of ugly ridiculous painted guitars - we are fronting terrible times for guitar lovers...