Bob,
Along with converting all my former H4350 loads to IMR4451 (which has gone very well so far), I'm also doing some of the same thing with H4831 and IMR7977. For the same reason, too--when H4831 becomes available, it's briefly and erratically, though not as much as H4350. Meanwhile 7977 has been pretty much constantly available since it was introduced, especially on Internet sites.
7977 not only works well in the .270 Winchester but various magnums from the .257 Weatherby to 7mm Remington to just about any .300 from the WSM to Wby. It's also one of the best powders in the .280 Ackley Improved, just in case you decide to upgrade from the .270 one of these days. :-)
I'm a little "gun shy" about all this new powder. I keep thinking that they produced a giant stockpile before it was introduced and when that runs out, these new ones will be just as sporadic as everything else.
Otherwise, I'd switch too. But I figure about the time I get some loads worked up, it will disappear.
At least with 4350 and 4831, you know that at some point, it will be back in stock.
