I'm with Dan on this.
I think it depends in what caliber... Do you know how they compare to Interbonds?
I used Superformance Interbonds in my 6.4 Creedmoor at 2950 fps on Warthog, blesbuck, bontebuck, 2 red hartebeest.. One was a pass through both shoulders, 4 springbucks (made pretty big holes), 2 fallow deer, common reedbuck (blew half the heart out the other side).... I will try GMX loads when I find some. I use SST and Amax for practice. Sighting in with 129 grain SST seems to get me right on with the 129 grain Interbonds
If SST's are softer, I would not recommend, if they will penetrate and hold together as well or better than the Interbonds, they should work fine at 308 velocity.
My wife used 150 grain GMX superformance 30-06 loads on black wildebeest, zebra, blesbuck, impala and fallow deer. Very effective. If you like superformance, why not use GMX bullets in Africa? They will hold together, mushroom perfectly but not as violently, and penetrate. We pulled a GMX out of bone on one of the critters and it held up perfect.