There is good and bad points to both ultra & mono coverings.

Ultra is easier because it does go around compound curves, has a higher shrink rate & it is easier to put one color over the other. However the glue activation temp is the same (LOW) as the shrink temp. In other words, hit the covering with a heat gun and the edges will pull loose. When you go to re-shrink or get a little aggressive with the iron the seams will pull apart. When covering with Ultra, it is best to put one color over the other. With Mono it is best to join the colors. Ultra also does not have the opacity or shine of mono. You can see wood, blemishes, and other colors through ultra covering.

Mono, what can I say, tough to work with, not easy putting one color over the other. (Windex works well if it's not a compound curve) If you can work well with it, you will end up with a better looking finish when you are done.

Generally, I like to put Ultra on my smaller less expensive planes and Mono on my bigger ones. Just my preference.