JCMS, no experience in .277, but quite a few of us in .308 Win and .300 UM and 7mm (Rem Mag and .280 Rem) and Bergers in .300 WM.
Good results all round, but weight was 168gr up to 220gr.
I've even used A-Max on smaller game in my .300 WM - Blesbuck and Springbuck, with great results.
As you know, not everyone feels the same about it.
I was required to shoot an Eland wounded by another in our party earlier this year at around 15 yards I think it was, with a 210gr Berger (MV 2830 or so). Right on the shoulder - he was dead in seconds. Do I recommend a Berger for something as heavily boned in the forequarters as Eland? No, but it did what was required (that time). I can't tell you how large a pice of bullet (or if all of it) made it to the vitals.
At medium / longer ranges risk of breakup reduces, but hitting heavy shoulder bones remain a risk I'd think. It depends a lot on what you are hunting.