Nakihunter-

The answer has to be qualified.

I can't say yes or no, unless I know who it is I'm talking to and what they're all about.

If you'd been raised, or raised yourself with a great and rich understanding of fine guns, their care, feeding, handling, and value...
If you were clearly competent to judge a piece of metal, forgings, weldments, mechanisms, finishes - as well as wood and woodworking, repair, stockmaking, gunstock finishes and fitting...
If you were already an exceptional marksman, handloader, wildcatter, bullet maker, gunsmith...
If you already Really, Really knew the potential issues around double rifles in respect to regulation and shooting/developing loads 'on the way' to successfully making ammunition for a double rifle...

and

if either you just couldn't afford a new one and wanted a challenging project - and could find a good candidate as a first double rifle/neat vintage rifle that needs help, is within your scope of capability, and you can afford...
(good luck to you in today's market!)

or you understand the value of the fine old collectible guns, can afford a solid runner with known good regulation, from a reputable source who would agree to a reasonable inspection period in the hands of a real-ass gunbuilder like JJ at Champlin Arms, and know you're capable of caring for it properly - so as not to risk losing a ton of cash while you're at it...

Go ahead on the neat old used guns!

Otherwise, I'm going to spread the advice of those much more experienced than myself in the collecting and use of double rifles and say 'Buy new!'

A new rifle from a good maker, sold through a good dealer and covered by a maker's guarantee, backed by your local dealer is the way to go.
Double rifles are so neat, so wonderful -- and can be such a frustrating bitch.
Expensive ones at that.
It's important to really freakin understand what you're getting into and either qualify for yourself that you're taking a big risk - and possibly losing the mystique and possible love affair with double rifles or just buy a solid new one and get out in the field and hunt out into the sunset...

--Tinker