My take on your two velocities, Upacreek, is this--and I hope members will chime in if I'm wrong. A lower velocity will aid a bulllet in penetration (especially on a design that's main attribute is rapid expansion) because it has less violent forces acting on it upon impact. The higher the impact velocity, the faster the expansion and therefore subsequent disintegration of the bullet if it has no mechanical aspect of the design to keep it held together (bonding, monolithic construction, partition, etc) within that impact velocity envelope.
There is also such a thing as too slow of impact velocity as well, which will fail to open a bullet if it is TOO tough due to the above mechanical features (bonding, monolithic, partition, etc) so it ultimately leads to the age-old question, which is the BEST bullet for 100% of likely hunting scenarios--that question has yet to be answered, as evidenced by the bullet discussions we all read on this site.
The SST will kill an elk, but the hunter must decide what angle he feels confident in shooting the animal. A close-timber quartering to/away or frontal raking shot might result in a wounded animal with a bullet that's too lightly constructed, but a longer shot with a bullet that's too tough to expand sufficiently might also result in a wounded animal.
Shot placement is always key, and a hunter must be aware of their bullet's capabilities in each instance.
In this instance, if the OP is going out strictly for longer range shots at Elk, then my opinion is that he should pick a bullet accordingly (high, BC, "lightly" constructed, etc) If he's going out for normal elk conditions, which are usually shots at 300yds or less, I would pick a bullet that might sacrifice on BC, but has a greater impact velocity envelope.
