I think that does clear things up. In short, its pretty much based on your xp on the given level you are working on. For example, if you were sittinng at 199/200 xp, you would be sitting at 199/100 after the patch, therefore, autoleveling on your next xp gain,(in this example, you gain 2 xp) and sitting at 101/X, where X=the number of xp needed to advance to the subsequent level? Makes perfect sense to me. I appreciate the clarification!
That is a good question about carry-over.
So, yes, let's use the 33% reduction and some numbers based on that.
Say I'm 800,000/900,000 XP for a level. Now, the level gets reduced to 600,000. I know I'll be 800,000/600,000 and ding on my next XP gain, but what happens to the extra 200,000? Does that get applied to the next level, or does it just get lost?