I'm glad you clarified that, Howard!
Because for a second or two there, it sounded like you were taking quotations from folks like G. David Tubb, and Norm and Rocky Chandler, and using their info to basically blow off the opinions of others of us who regularly compete at 1000 yards. (Myself, with a 6.5-06 for several years at places like Sacramento Valley and Williamsport) Bogie is a regular here who does serious long-range benchrest work, and he makes my 8" 1000 yard Interdiction Rifle groups look weak in comparison to what his Stolle Panda/Shilen beauty can do. Then I'd have to wonder why you asked for help choosing a 1000 yard cartridge to begin with...
I don't doubt that if anybody can burn out a barrel with a 6.5-284 it's G. David Tubb himself. But then again, he certainly can afford to push things to the extreme limit, he has sponsorship and lots of trophies. I was poor, and started out with P.O. Ackley Volumes I and II early in my wildcat cartridge career.
If you're serious about taking things out to 1000 yards, even if just occasionally, don't cut off your nose to spite your face with a 20" barrel. There are more than enough variables (ie, temperature, altitude, winds, mirage) that will creep up and make things difficult at that distance, transsonic bullets don't have to be one of them. Swinging a 24-26" or longer barrel isn't that much more difficult.
Don't forget, if you settle on the 6mm/.243 as your long-range round, those Berger VLD bullets will require a fast 1-8" twist for the 105gr bullets, and a faster 1-7" twist for the 115gr VLD's. Not a bad thing, but something to remember when you order your barrel from Krieger/PacNor/Shilen/Lilja.