I think the whole spiel about shorter cases being better for long VLD bullets - when the max loaded OAL is the same - is baloney. In this case, 140-gr-class bullets will have bearing surface well below the bottom of the neck (ie, not above which can help avoid "donut" problems in some circumstances).
The 6.5 Creedmoor and the 260 are virtually indistinguishable looking at ballistics, and I expect, accuracy (based on my 260 results anyway). 260 has a lot more brass choices.
MDeViney,
Ray and I have been shooting partners at some team matches, and we both owners of TBAC.
-z