Personally I love the list, I think it has a bit of everything, and will be a fun one to play. I'm no guard expert, but it looks solid.
Something to consider, though:
Plasma guns / metal guns argument.
For guard, as you know, your infantry aren't... the most durable, and rely a bit on numbers and cheap points to offset their toughness of 3 and 5+ armour save. Plasma guns will get hot eventually, and a 5+ armour save is not a reliable bet to take when trying to save yourself from overheating. However, they do outrange the melta gun, and rapid fire with strength 7,
ap 2 weapons are never a bad thing! Just consider, though, that if you want a less risky option, go with metlaguns in your infantry squads. Which ever way you go dpedns on your play style though, so don't let anyone tell you one is WAY better than the other.
Have fun in the games you have with this list, and tell me how they go!