I've been thinking about the list the last few days after putting my thoughts down on here. I think I've overlooked a few things, mostly war gear and the roles of the various units.
I was thinking of arming up some of the Vanguard formation with plasma pistols and also give combi-plasma on my Sternguard. This means that they would both be going after ap2 targets, a possible clash, as in my view assault troops shouldn't really be assaulting 2+save units, unless you can out numbers your opponent by quite a few hits. The only issue comes with the fact that the pistols will be able to fire every turn where as the combi's are a one shot weapon and if I don't manage to eliminate the target, then I could suffer. I have generally found that most armies only contain one 2+ save unit and that a unit of Sternguard plus some other units, namely the Vendetta, can usually deal with them along side massed fire from my guard. This means that the assault marines I planned on arming with plasma pistols maybe unnecessary, or I can drop the combi-plasma's. Alternatively, I was planning on arming up the other assault squad with infernus pistols, but I might be better arming the Sternguard with combi-meltas instead. This means that I can leave the plasma pistol assault squad and drop the infernus pistols, with their short range. But then this means that my Sternguard become a bit of a jack of all trades unit, rather than the dedicated hunters that they should be.
Another clash could well be between the MT's and the Sternguard, as there both ap3 hunters, the MT with HS lasguns and Sternguard with their special issue ammunition, although the Sternguard have more flexability, the MT's do have more numbers though. Personally I like the Sternguard due to their flexibility on the battle field but the deep strike ability of the MT's has proved useful in the past, even if its not that reliable at times.
It's not easy to decide what would be best, hopefully I'll be able to get a few games in to test out my options. One option is just to drop one of the units, and that will free up lots of points for lots of options. However, I just don't feel like doing that and much prefer to shoehorn in as much as I can. Silly, more then likely; competitive, no probably not in the slightest, but hey, i think it will be fun.