Duramax,

I've had a .45 cal inline CVA for about a year and a half now. I personnally like it, although it has taken me quite a while to find loads that it really likes. I've taken 1 deer (medium-sized buck) with it - dropped in it's tracks at 108 yards. Here are some pros & cons based on my limited experience:

Pros:
-Better long range perfomance (in theory) because of the better sectional density and ballistics of a .40 cal bullet saboted (such as a 200 grain shockwave, or the lead/polymer tipped offerings from Traditions).
-Can use light bullets & low powder charges if desired (i.e. low-recoil loads for those who don't like recoil - children, for example).

Cons:
-The better long range performance is probablymostly on paper. Everyone that I know that shoots at long range (150+ yards) uses a .50 cal loaded with SST/Shockwave-type sabots.
-Harder to find bullets/accessories for it
-They have a rumor as being finickier with loads - while this may not be true, it has been true with my rifle - it's taken many range sessions of messing around with different combos to find something that has good accuracy.

I got that .45 because it was on sale, because of the supposed long-range superiority and just to be different (because EVERYONE has a .50). I don't regret it, but I honestly can't say that it has a lot of advantages, either. It'll kill deer just as dead as a .50 cal, no problem, though.

Hope this helps!