Congrat's Joe!
Personally, I've seen elk hold more Accubonds than Partitions, likely because they open up to a slightly bigger diameter. Either way, I don't see any real need for an exit hole and your AB's performance is great IMO.
I'm planning on trying 130,140,150 Partitions and 140 NAB's in my 270 MT... whichever shoots the best will get used.
Brad, on our trip this fall, my friend who'd never even taken a deer before, took a grand 6x6 bull with his 270 at just over 200 yds. It was a perfectly placed broadside shot with a Premuim Fed 150-grain Nosler Partition. We shot over the summer familiarizing him with his rifle (Tikka) and load. It chrono's at about 2800+ fps from the 22" tube.
Tucked right behind the on-side shoulder, the NP was picture-perfect having lost its "nose" enroute to its resting place, as is usual, just under the off-side hide. The bull took a very short twenty step or so trip before quitting.
I don't think you will be hindered by any of those choices though I might lean toward the heavier weights myself.
