Was at the LGS the other day and overheard two gentlemen discussing the 26 Nosler - specifically, guns chambered for it. One gentleman had had the Nosler Patriot in 26 Nosler and traded because he could not find a load (commercial load) it liked. So happens he traded into a Browning X-Bolt LR Hunter in 26 Nosler. Sounded to me that to this point he hadn't had any luck finding a load the Browning liked. On the other hand, the 2nd gentleman was professing his love for, and the accuracy of, his Christensen Arms Carbon Classic in 26 Nosler, regardless of what it was fed.
Now, in this case, whether one guy was trying to impress or BS the other I don't know. I would hope that for the money spent, the Christensen would shoot well - hopefully better than the Browning. The difference in cost should at least buy you that.
All that said, the OPs mention of grouping issues with the Browning X-Bolt 26 Nosler doesn't seem to be the first of its kind.