Well I've had a .54 Great Plains flintlock for a little over two years now. It's my first and (so far) only flintlock. The only modification I've made to it was to install a RMC touch hole liner before its first shot, and a Lyman peep sight last year.

I've got to say;
(1) it fits me as well as any gun I've ever owned - feels just fine at the shoulder,
(2) it's more accurate than I'll ever be with iron sights,
(3) it has functioned perfectly from day one,
(4) I average somewhere between 40 and 60 shots per flint,
(5) It seems to me to be as fast as my caplocks, at least most of the time,
(6) Fit and finish are acceptable for a production gun - decent but nothing fantastic.

So why do I now have an itch for a custom flintlock? I guess it's as Cayugad said - a desire to own something unique and very personal. Art appreciation? Possibly. Vanity? Also possible. Still, I'm finding it difficult to justify dropping $1400 on a custom rifle. That's a lot of bucks for me. It's hard to imagine I'll enjoy shooting it any more than the GP, or any of the Hawkens, or the Renegades, or even the Omega. But the itch is bad.