I'd rather keep the reinforced armour, these guys are going to be getting in the face of the opponent as a spearhead/breakthrough formation and I think with the reduced save they will be too vulnerable to attrition, if we think they are too tough (and I'd rather base this discussion on the intended role of the troops rather than 40k fluff) then I think making them into light vehicles would be a logical step to increasing their vulnerability to a range of attacks
I agree making a single statline is tough as the two variants are very distinct, as they are currently, the dev variant has a twin lascannon and two twin heavy bolters per stand, while the assault variant has a twin heavy flamer, and siege drill
I'd rather keep ranged macro weapons out of the list as much as possible, and would prefer to stick to established weapons, the combined statline was suggested by osoi and with some discussion between us we hammered it out to
INF 15cm 4+ 5+ 3+
twin short barelled lascannon 30cm AT4+
Siege Drills (close combat) EA+1 MW
Hurricane Bolters (small arms) EA+1
+
possibly heavy flamer 15cm AP5+ ignore cover
reinforced armour, transport as terminators
so they work best as a FF engagement/support unit, while they have MW combat attacks, the cc5+ will make them less effective, I'm reasonably happy to test them out at those stats, but wanted to see if there were other options for the main shooting attack that didn't involve inventing a weapon
happy to try other stats out but so far nobody has used centurions in their games so we have zero data on how they perform!