I've been cataloging all of my content from this last year (over 1TB) and doing a LOT of edits and conversion (mainly in MPEG Streamclip) but for all my Alpha visuals I am using Premiere and AME. I have a LOT of presets for sessions and exports (23.976 - 60 fps @720p AND 1080p) if you would like me to send you a link to add to your presets? presets are for ProRes 422(HQ) and 4444 for Alpha, as well as DXV3. All presets are set for standard export and with Alpha. To repeat what Oaktown has said, Alpha requires a 32bit export to work (sadly MPEG Streamclip does not offer this, unless I've overlooked it somewhere?)
Let me know if you would like a download link. I'll be traveling on a gig the next day or two but i'll try to get to you before i leave if it's time sensitive.