That is amazing accuracy out of a muzzleloader! It's incredibly satisfying to work a load up and see those kind of results at 100 yards. I did the same with mine this year and it went from "I wonder if I can even hit paper at 100 yards" to "I wonder what my grouping will be at 200". It's incredible what these modern smoke poles can do.
This combo works great on paper. Hope to see how it performs on deer.
I may be able to provide some insight on this, but not from personal experience. I've done some pretty extensive research on my bullet/powder combination since this will be my first year really hunting with my muzzleloader. Just like you, I started out shooting Hornady SST bullets through my gun. I have a .50 cal and they were 300gr bullets is the only difference. I too experienced excellent accuracy with them, shooting about a 1" group at 100 yards. After the fact, however, I began doing some research about those bullets.
What I found was interesting. I've used SST bullets before in rifle applications with great success. I even witnessed my dad take his LE elk at 500 yards with 30-06 Hornady SST bullets. They seem to work great. But for whatever reason, a few people that have written about them and talk about poor performance.
Here are a few words written by outdoor writer Randy Wakeman about the SST bullets in a muzzleloader application:
"The Hornady SST has been seen to exhibit very poor terminal performance; the touted "Inter-lock" design is not evidenced in the dissected bullets."
"The XTP is a far superior terminal performer compared to the Hornady SST; there really is no dispute about that."
http://www.chuckhawks.com/underrated_hornady_XTP.htm
With that being said, I don't imagine a deer that could survive having a .45 caliber hole punched through the vitals. He doesn't ever really cite exactly what he found or what the bullet did that he found unpleasant so I would take it with a grain of salt, but it's something to bear in mind regardless.
Again, I really liked how the SST bullets shot out of my gun. I would have taken them deer hunting had I stopped there. But since my initial sight in, I decided to pick up a box of 300gr Hornady XTP .452 pistol bullets and pair them with Harvester Crush Rib sabots to try out. I found them to be equally as accurate as the SST bullets. I even shot them at 200 yards and shot about a 2" group. I am more than pleased. And after doing a bit more research, I decided those will be the bullets I am hunting with.
I hope this provided a bit more insight than anything. I don't want to steer you away from using your combination if you feel confident and comfortable with it. No matter what you're using, shot placement is key. An animal simply can't survive a shot through the lungs and/or heart. Good luck to you in the field this year!