Go to Vaportrail's web site, they've got some highspeed video of the rest being shot, it clearly shows that it stays up for a good long time.

I think the big draw for the Limbdriver is not so much the time it supports the arrow, but that it's not slaved to the down cable,rather to the limb. A "traditional" dropaway cord is loose at brace, and gets tigher as you draw; the Limbdriver is the oppoiste, it's slack at full draw. Not necessarily a big deal for a single cam bow, but the the force from the traditional dropaway's can have an effect on binary cam bows. The presure from the cord adds tension to one cable but not the other.Since the binary cams are slaved together, you can end up havingtiming issues; IE one cam hitting the cam draw stop before the other. Tuning problems and letoff issues can result.

I don't think this is so much an issue with the newer (06 and up) binaries, but lots of Bowtech guys use them. I may be mistaken, but I think the Limbdriver is what Bowtech reccomends for thier bows.