yeah good plan - that's what I mostly use my Deathwatch for (built the squad when they got their White Dwarf rules introducing special ammunition, before the Marine Codex... and since they are just plain better as Sternguard, and my mates know exactly what they are (some are our very own Deathwatch characters from the RPG) they don't mind if it's not exactly WYSIWYG...). A bunch of combi-meltas are very useful outside of Apoc as well - especially with the ability to Combat Squad the bunch to avoid overkill...