Never given a shit about Dio or Sabbath. For some reason I'd still prefer Dio though.
Summoning is probably the most boring crap I've ever listened to and the drums in first few albums sound like beats taken out of some cheesy rap songs.
Cannibal Corpse should replace Ma-jerk-ovitschschsgehfldmsbsbd and find a more frantic drummer
No, no they fucking shouldn't do that.
Though if the band itself is getting burnt out on their old formula I'd rather they take a risk and try newer inspired shit vs shitty music they clearly weren't into when writing it. (See: Ghost Reveries/Watershed vs. Heritage/Pale Communion)
That would be like AC/DC putting out a prog rock album. It'd be terrible.
There are times where you don't fuck with a successful formula, lest you lose your stride.