IMHO you don’t take the combi-bolter armed guys for the dakka, but for the fists. There are far better ways of getting some more light fire downrange then these guys.
I think running them mostly with claws is the way to go. At least one chainfist, in case you need to open tanks up, and maybe a power fist just to crush heavy things. While you can’t overwatch the
HF, it might be worth bringing along. Doesn’t cost that much.
What to give the sarge is a big question. Harness is probably a given. 2+/4++ is probably tough enough to survive to punch at I1, but that’s a question about how much risk you are willing to take. Fist or sword I think are his best options. Chapter tactics and other outside buffs can make a big impact here as well. Ultramarines, with the ability to use the assault doctrine when needed, makes the
MC sword worth less. Same if you are going to stick a chaplain in with them.
Looks are also a factor if you let them be.
If I had my squad to build over again, I’d go with something like this:
Sarge: combi/sword, harness (I like the look, honestly think fist might be the better call here)
HF/Fist: Sometimes things need to burn
bolter/chainfist: I want the chainfist, but don’t want all my eggs in one basket, so not pairing it with the
HF 2x Double
LCs: To blend
MEQ and softer foes.
It mirrors the ratio I keep my terminator assault squad in (3xTH/
SS, 2xLC) Some hard hitting guys, some wounds spam to deal with chaff. But instead of all the durability in the
SSs, you have a 4++ all around. And get a little armorbane and some shooting, rather then concussive hammers.
What I actually built mine as was
all lightning claws (harness for the sarge) But this was before the supplement gave them
40k rules, and I needed more assault marines to balance out the shelf.
And they don’t look like very nice guys. I think of the squad as “I can’t believe they're not Night Lords"