in my experience seaguard aren't really worth the extra points. they have regualar bows and the extra points soon adds up. as you want to maximise rank bonus so they don't get owned on combat res then you end up with 5/7 shots a turn, having to move on the first turn, INTO there range if they are a shooty force and therefore hit on 5's. if your lucky you may kill 1 low T low Armour model in the first turn maybe 2 in a normal round.
Or you can have more points elsewhere?