I'm not too familiar with the LTD Fury but with a size 45 you'll definitely want to be riding a wide board, especially with a mountaineering boot. If you have 2 inches of toe drag and no heel drag then your bindings aren't centered, you should move them further towards your heel. Maybe you were thinking that I asked if your stance is centered?
I'm actually kind of curious to see how the Spantiks ride but I think I'd be more apt to spend the money trying to convince a good cobbler to modify a good pair of snowboard boots before I'd try to snowboard in a good pair of climbing boots.
If you're fairly new to snowboarding and really want to do a lot of mountaineering with your split then you should should probably just sack up to hard boots. I put some time in riding on a pair of Koflach Superpipes when I was 12 (before I knew they were cool!) and don't think I can give up the soft boots at this point but AT boots would almost be able to do what your Spantiks do for you but also allow you to ride plate bindings. I don't think you'll get enough response on the heel side to do that with your boots now but I could be wrong.