I wish you could reject clips in KeyFlow Pro but you can’t at the moment. The only “workaround” is to add “Reject” as keyword then create a smart collection in FCPX where you can actually reject the clip range. This is not ideal but it works.
There is also Kyno but it is overpriced in my opinion. Have yet to try CatDV so no opinions there. Craig, what frustrates you with CatDV, just curious?
One thing I have noticed is that there is a KFP users group on Facebook but there are less than 100 members in there.