Hyperdeck
The need for a clip player that holds an alpha channel has in the past required a thunder or a x-clips, a pretty expensive solution for local broadcasters.
Clip players are generally used to play franchise opens, animations, and transitions. Things that don't require any replaceable elements, and have a pretty long lifespan.
A less expensive and equally as powerful solution is black magic's hyperdeck
http://www.blackmagicdesign.com/products/hyperdeckstudio/
they don't have an alpha line out so purchase 2 of them. Put the key in one and the fill in the other. The decks have RS-422 control so your switcher can treat it like a tape deck. Set up a timeline on your switcher that slaves the two hyperdecks together and pulls the key.
here are some instructions from Joel McDonald on setting up clips in the right codec.
Exporting AVID DNxHD codec from EDIUS
1. From the PRINT TO FILE menu select QuickTime Canopus HQX SuperFine 10bit 4:2:2 and Click Export
2. Click the Settings Button
3. In the Video section of Movie Settings click Settings…then select Avid DNxHD Codec from the dropdown menu