The HIPS of Comodo and BB of Avast doesn't overlap since they are 2 IPS that works differently, they may detect the same malware but the way they treat it is different.
When i used this combo, i kept the SB of CIS and discarded the one of Avast, at that time it was more convenient.
im quite surprise that Comodo AV surpassed Norton AV, in all detection tests i did, not saying that NAV is very slow compared to CAV or EAM...
I set NAV's heuristic on aggressive everywhere, allowed the cloud, etc...
I really think now that Norton focuses on prevention by putting all the power on Sonar.