Since last hunting season I have sold all of my muzzledloaders except for my TC Hawken. Honestly, I just wasn't completely happy with any of them.
I am all for being the 'man with one gun' but it seems to me you have to get a handle on what suits you.
What did you like/dislike about what you had before? Make sure you capture the likes in the new one and lose the dislikes.
If you buy a discontinued model (the Vision) check with Knight (Athens, TN, and CS) to make sure you're not left with another disappointment if you need parts or labor.
In the short term, hunt with the Hawken for now, while your young and your eyes (if you are using iron sights) are up to it. I was pushing 40 before I gave up and got a scoped inline. And I still go primitive when I feel up to it.