The weathershield barrel on my son's Triumph (silver color) is holding up very well, no chipping, no rust, the rifle is going on 4 yrs old. My younger son's TC impact has the same weathershield barrel (just a tad darker in color) is also holding up well but that gun is only a year old but I foresee it lasting for the life of the rifle. I have seen some TC muzzleloaders with just the blued barrels and they did have a very slight rust color on them, they were display models on the shelf and I doubt they were ever wiped down at the end of the day. I have read a few reports of some being disappointed with the quality of bluing on some TC muzzleloaders so thats why I always went with the weatheshield.
I also use TMZs, both 250 and 295. They fit tight but thats the way I like them. I use BH209 so reloading is not a problem but it could be using T7. The TEZs are basically the same bullet minus the boattail and have an easier loading sabot, that may be an option for you on the second shot.