I play both the Wild Thing Bb and the Flip Oakes C for mostly legit applications. I have always said that it is a great horn for this setting even though it is marketed toward more commercial players.
What sold me on the horns was my ability to be more expressive on them than on others. It is easier to play with more dynamic range and depth of expression. Like other instruments, there are some pitch issues that I had to deal with, but once settled I am very happy and have improved my playing using them. There are never issues of blending with all sorts of other instruments including Bachs and Monettes.
I think Flip has a great instrument and would recommend it highly to anyone, ESPECIALLY orchestra, soloists, and brass ensemble players.