Not much I can add to the info above, except to say that it took me around 25 years to come around to Thunderbirds, and wish I'd done it 25 years earlier - so don't leave it too long to at least try!
I'm lucky enough to own a '65 IV, and it's hands-down got the best passive tone I've ever heard, and is the second-best ergonomically to play of all I've tried - the best being the Gibson Explorer, bizarrely enough
The new ones seem pretty decent mind, and cheap enough second hand - for those new prices quoted, reckon I'd go for a Lull over a Gibson