I think the 170 Berger just doesn't like to be shot over 3200 fps, especially in such a fast twist barrel.
Hmm, I don't have any problems running them in a "Kirby Built" .270 Allen Magnum, 30" Lilja, 8t at 3400fps (US869). This is a 3 groove barrel and there's reports out there of once these barrels get a few rounds through them they start "gnawing" at the jackets. So far I haven't had any problems but the round count is still quiet low, as in may be 250.
I really appreciated the info you gave for the .270 Boondoggle. I extrapolated your data to the AM. I haven't tried the 145gn ELD-X yet but I did try RL33, GM215M's and the 169.5gn Wildcats and found it had a narrow window of operation. I started at 93.0gn and was knee-deep in pressure right to start with. Tried 92.5gn, still there, so went to 92.0gn and it was just on the edge. Velocities were 3498, 3475 and 3463, respectively. Still needs some tweaking.