Level difference/cap for XP

[Twisti]

I read in one of the patch notes that you do not gain any XP from mobs more than 10 levels above you anymore.

Now, for the most part, I have found that to be roughly true, however I arrived in act IV, normal with 0 XP (level 1, obviously), but I got about 50 XP during killing Big Red. I did not attack Diablo or anything else. Where did that XP come from ?

Also, the cows in the SCL are all level 28. Yet, everyone you ask says not to go there before level 20 (instead of 18). After testing it myself, I really got close to zero XP at level 18 and 19. Whats up with that ? Is the '10' wrong ?

[Twisti]

On that note, could someone tell me the other jump-off points ?

Min level for Normal Andy runs: ?
Min level for Normal Tristram runs: ?
Min level for Normal Tomb runs: ?
Min level for Normal Cow runs: 20 ?
Min level for Normal Baal runs: 25
Min level for Nightmare Andy runs: ?
Min level for Nightmare Tristram runs: ?
Min level for Nightmare Tomb runs: ?
Min level for Nightmare Cow runs: ?
Min level for Nightmare Baal runs: ?
Min level for Hell Andy runs: ?
Min level for Hell Tristram runs: ?
Min level for Hell Tomb runs: ?
Min level for Hell Cow runs: ?
Min level for Hell Baal runs: ?

[baffle]

If you're really looking for the fastest levelling, and can get rushed there, then:

Min level for Hell Chaos Sanctuary/Diablo runs: 1

Simply the amount of experience from each monster is enough to compensate for all penalties.