I have used both on deer. .270 Win (130g GK) and .257 Roberts (100g Speer). The .270 was used on several deer and one antelope. The Speer on one deer.
The GK was totally unreliable inside 200 yards. The only animal shot beyond 200 yards was an antelope at 360 yards. That was the only GK that exited and in fact the only one that hit the ribs of the offside. Every other one came apart even on smallish deer before hitting the offside ribs. This led to dramatic kills or deer that needed to be shot again because the bullet failed to penetrate enough when heavy bone like shoulder was hit. It has proven very accurate however. I have decided if I use them again for deer I would go with the 150g as you are asking about to see if they would give better penetration.
I only shot one deer with the Speer. It hit just in front of the shoulder causing a big entrance hole and no exit, killing the deer. Speer does say the boatail is softer than the "Hot-core" and is meant for long range shots.
