Only time I solo killed death was last patch when Cleverness gave too much early exp and I abused it to get Abomination absurdly fast. Then I led all the jungle creeps to one place and got a cleaving item.
"Bahamut - Finals - Death" for me all 3 had different handicaps. I cannot tell that a hero can kill death also kill finals. I give a chance to BS to kill all 3. Also Finals avoidable as far as i remeber 1 of your dark ranger replays you fight death skipping finals.
About solo quest, i totally agree with you. I prefer also more single player quest. At some old versions we got some quests with specific conditions: No hire unit no towers. Maybe there might be same quests. Probable to add -sm quests fot single players.