Meadowlark Ospreys.. fighting under their weight class?

You have great electronics so the chances are whatever speakers impressed you at the show will sound even better in your own home. At least that's been my experience, albeit limited, when I heard speakers at shows in those dinky room setups.

At CES you listened to complete systems, not just speakers. Its just something to keep in mind. Your current speakers are still very good. The one recommendation I would make is once you get used to time and phase correct speakers, its difficult to listen to other designs. Since you heard and like Vandersteen, I think that would be your best option. Your current speakers are very laid back. Vandersteen's are more lively without going too far.

GTS1 - if you gotta scratch that itch...

One speaker that springs to mind and in your budget, that would work very nicely with your gear - is the Tannoy Prestige line. 

They can be a little difficult to source, but coupled with tube gear, will   provide a smooth and effortless life-like reproduction.

Don't let the looks fool you - they do look a little "old fashioned" but for years Tannoy has employed advacned features, like cabinet bracing, that other brands are now advertising as "advanced".

A friend of mine in audio sales has told me that most people that buy Tannoy seldom replace them. 

Something to think on

 

+ 1 for Tannoy , you have system made in heaven for them .

Budget of $15-20K? You should not even be thinking twice about this! With a budget like that you will be able to procure a transducer which would walk all over the Osprey's performance. It's a simple matter of what you get for the money. The osprey may be very nice, but it's obviously limited much more so than a great number of $15-20K speakers. You can get into an entirely different class of performance. This is one of the questions that the obvious answer is yes, make the move. 

With a budget like that you also should consider whether you want a panel speaker. Completely different world with a big panel as opposed to a smaller tower like the Osprey. You have a LOT of room to move upward in performance no matter which direction you go, and it seems you have the motivation and means. It would be a shame for you to get stuck with a smallish tower and never get a slice of the experience of a larger, more capable tower.