In my experience the smk kills dead, just as dead as dead could be but if you don't hit in the vitals you will have trouble. I have shot goats at 1400 yards with 140g 6.5 smk from a 6.5/284 and they go straight through, in one sholder and out the other . The exit hole is about 1 inch or less. In one case I hit the goat I was aiming at and the smk went through it and hit and killed another goat that was about 10 yards away. for the experts, the projectile changed trajectory about 40 degreed up when it passed through the first goat and the second goat had a J shaped hole in the entry side and no exit. I recovered the projectile and it was broken and a portion of the nose was missing,one of the petals.I was at about the same elevation as the goats,they were on one hill I was on another hill. the second goat was about 6 feet higher in elevation than the first and about 3 feet to the right. both goats were facing left. I have also used 168g smk's from a 308 on pigs and they did the job better than the factory pmc 150g ammo. I think because they could punch through the sholder better. the pmc ammo had a tough time getting into the vitals at 500 yards .just for the record these are feral pigs and goats in australia.
another thing to look at is your local laws. match projectiles are classed as FMJ. make sure that you can hunt with FMJ in your area.now as you know sierra make a game king. the only difference in construction and materials is the size of the hole at the pointy end as far as I can tell.
In my realistic opinion here un the US of A where every one is watching what hunters do. don't do any thing that will make them make laws agains long range hunting. like wounding animals. lets face facts here we have no chance of chasing the game from my experience. I shoot watch and then walk to the area and collect. where the 100 yard guys are alot closer and can follow a wounded animal quicker and easier. so I say If in doubt dont do it.