Well if the do as advertised (which is rare it seems with regards to over marketing of new/better bullets) it should be an excellent choice. I shot the 150Gr version of the SST last fall and it did a marvelous job on a large whitetail buck (350 plus on the hoof) at 127 yards and a bull moose at 200 yards. While I never planned on using it for bigger game nor would I suggest so, I was very suprised at how well it performed on a decent sized bull moose, he piled up in no time and left a blood swash that anybody could track. Both shots were with handloads and double lungers.

Now being I have used 130 Gr. Nosler Ballistic Tips out of a 270 for several Mulies and Whitetails harvests, I could easily suggest trying either the NBT or the orginal SST if you can' t get the IB to fly well(BTW, I have had no luck getting my hands on the new IB to even try as of yet, maybe your shops are different). Our mulies and wt are large bodied animals with many tipping the scale well over 300 lbs, I have taken both game at short to long range with 130 polymer tipped bullet with excellent results. The NBT or SST should not have the same rapid expansion in longer range shots as close range, therefor the concern for blowing apart should be less. What they will give you is better expansion/penetration at those long ranges...in theory anyway. IME the up close shots are the ones that cause the fist sized holes. Provided you can hit the H/L at 400 yards they should work fine. However if you aim for bone (ie pins/shoulder blade) I would stick with a bonded style bullet (Nosler Parts, interbond, etc).

Good luck on finding the bullet and the Mulie