Rey, I thought this battle is over :-)
To sunmmarize
1) You agree that incremental checkpoint and slow checkpoint are quite different and I did not see any serious difference with what I posted here
2) You claim that if you have DB Buffer cache well configured, you'll never face slow checkpoint. Well, if I try I probably can find a case when that's not true, but generally I agree
3) If I understand rigth, you claim that archived logs are needed during the instance recovery in case if a transaction is longer that the total size of the redo logs. Sorry but your example did not prooved that, and it cannot proove it because it is not the case. What if thet database is in noarchivelog mode? You will prohibit the long trtansactions or the instance recovery is not applicable to noarchivelog mode or it will fail in case of long transaction?
I am saing that maybe for thid time in that thread but I am doing so, because I am completely sure about that - The size of transaction have nothing to deal with the checkpoints. What is keeped and needed until the transaction ends is the unod. Redo has nothing to do with that. As ixion mentioned, the undo itself is covered by the redo mechanism.

Maybe it is a good idea to make an article about that

Regards
Boris