I saw Absinthe last summer. I have not seen Desir.
Absinthe was fun. Took place in a small tent so you are fairly close no matter where you sit. It has the feel of a small side-show like theater event with also a Cirque Du Soleil feel but maybe when they were small and new.
The show is more adult in nature than even Cirque's Las Vegas Zumanity.
I liked it. I do recommend it. Not too sure I would repeat it. I have considered Desir but don't have the push yet to go.