We have quite a few members here that have an assortment of AR calibers but I don't recall anyone with a 6.5 Grendel.
That's not to say you won't get any good replies though.
Would you mind running down your list of pro's/cons for the 6.5? I myself chose the .458SOCOM as a compliment to my AR15 and AR10. Although I have had my interest raised in some others - the .260 looked very interesting, as did the .338 lapua
If you do proceed please do a build thread for the rest of us to follow and drool over