It seems to me that the Cicero crew and Grand Ave had some of the roughest guys in the outfit. Although the 26th st crew had Calabrese brothers and Ronnie Jarret who did a lot of rough stuff as far as killings go.
The evidence against Aiuppa in the Strawman case was pretty weak. Pretty much the same as they got Lombardo on in Family Secrets. The same with Cerone. All they had on Aiuppa was a wire tap of a mobster using Aiuppa's nickname and a handfull of informants with 2nd hand information.
I think the reason Aiuppa and Cerone lasted so long was they would kill anyone who they suspected of being a informant. DiFronzo definitly pulled back on the violent end of things compared to Aiuppa.