This thread has been interesting. I have been able to get at least 2675 fps from 22" barreled .30-06's for many years, using published data for H4831, generally with excellent accuracy.
Haven't fooled with RL-26 with 200s in the '06, but have in other cartridges, and have not been impressed with it's temp-resistance. It's far better than RL-22, another powder known for high MVs in the .30-06 with 200s, but not as consistent as H4831. But then I live and mostly hunt in the state with the widest spread of recorded temperatures.
If you hunt somewhere the temp-spread isn't as wide, RL-26 would no doubt work well. But so far I haven't found enough advantage to switch, especially for another 50 fps or so.
