I've been fortunate with 700's.. but admittedly have never owned one in a "hunting rifle" type profile..
I've owned 3 of them.. all in .308 Win.. all custom built for precision/sniper type work.. all were incredibly reliable.. and all were sub .25 MOA rifles..
2 were "sendero" variants, the third was a 700P (police).. I had the actions trued up, timney triggers installed, McMillan stocks fitted, etc.. and they all got higher end optics mounted as well.. 2 were "play" guns that I just enjoyed shooting at the range (we had a 600 and 1000 meter range not too far from where I lived back then).. the third was my actual "duty" rifle when I served as a sniper team leader on a metro area SWAT team for a while.. I trusted my life and my teammates lives to it on more than a few occasions..
I genuinely loved shooting all of those rifles.. they were as good or better than any other "sniper" rifles I have ever seen/shot for engagements from 50-600 meters.. (there are certainly better options for engagements further out than 600)..
All that said.. I would have zero desire to take a 700 on a buff (or any DG) hunt..
While I am sure hundreds, if not thousands of DG around the world have been taken with 700's.. I guess the question would be... "why"?
If you can afford a DG hunt, you can afford a new rifle if you dont already own something suitable for DG..
And if Im buying a 700, only to have to spend another couple of hundred bucks to have an AR extractor installed, and have other work done to it.. Why wouldnt I just buy something off the shelf thats suitable as soon as I take it out of the box (Ruger 77, Win 70, etc)?
Again.. dont get me wrong... I know a 700 in 375 H&H will kill a buff just as easily as a Rigby in 375 H&H.. and I have long been an advocate for a 700 (when it doesnt have a QA/QC issue, etc) under the right conditions.. There is a reason it has been deployed by hundreds (probably more) major metro SWAT teams and by every branch of the US Military's SOF units in some of the worst possible conditions (rain, snow, heat, sand, dirt, etc) when other options were available to them..
But for me... it just doesnt make sense for a first choice for a DG rifle..