Hi,
If you're looking at a pair of klipschorns, and have the corners to fit them in, I'd say go for the klipschorns! when placed properly (in a corner, with their rear section snugly fit into it), these beauties go down to 17hz! I've heard klipschorns with tube gear, and it's like a match made in heaven.
The cornwalls on the other hand are easier to place since they are less room dependent, but bear in mind that they have a dip in the 300-600hz region, and have a nasty impedance spike around 60-80hz.
Pros and cons in a nutshell.
Remember, whichever you buy, do not hesitate to go over the crossover networks and freshen them up a bit (starting with the caps), it's a quasi mandatory thing with older klipsch gear.
My 2 cents.
Regards
Nick

The RF-63 is a great speaker for its class, and very less room-dependent than the Klipschorn, but IMHO they don't come close to providing the pinpoint accuracy and imaging the Klipsch Heritage line of speakers are capable of, mainly due to the fact that the RF-63 has it's woofers crossed at 1700Hz with the horn, and at 1700Hz you get a ton of audio (vocals, many instruments, etc...), adding to the fact that these woofers (3 of them) are spanning some 24 inches, you can see how a lot of the pinpoint accuracy is lost (and that's without mentioning the tweeter horn that sits another 7-8inches above the top woofer).
Compare that to a Klipschorn that has its low frequency horn crossed at 450Hz, while the mid and tweeter sit right on top of it, and you get a pretty solid case in favor of the klipschorn.

Now this could go on for pages should we note all the pros and cons of each, but that's it in a nutshell (and of course, as you might have noticed, i'm slightly biased towards an all horns setup )
Regards
Nick

The Cornwalls or the Klipschorns?

As Steve Deckert once said, "the amp will make Klipsch sound better than they are." or something similar to that.

It takes 20 minutes for the OC2 tube regulation to warm up to full potential. Also the unit is in burn in status and will get even better and stronger sounding with time.

Congratulations on your acquisitions.
How about you post some pics of your setup?
Klipschorns are always great to see in a system.
btw, make sure they fit snugly into the corners, huge difference between snug fit and a 1 inch space btw...
What model are they? what crossover type?
Ok, enough questions for now.
Congrats again.