Okay, here's the deal.
Both JTRH and KDD2.0 have the 2.0 engine, and an editor. Here are the differences.
JTRH
*Is the sequel
*Uses the new elements
*Has a more involved plot
*Is slightly more difficult
*Has a secret extra area.
KDD2.0
*Doesn't use new elements
*Almost all rooms are exactly the same as there AE counterpart
*The only major difference between KDD2.0 and AE, is that 2.0 has more talking, and it now has some extra secret rooms that are hard to find.
You decide which you want! I have both.