Walter, have you seen the new Sirui that just was announced? it looks quite good...what I would love to see if some type of mash up of the quick deployment on the YC Onion Pineta (Or the new Sirui) with the locking pedal of the iFootage. Each one looks quite good, but the combination of each's main features would be the one monopod to rule them all, imho...
Not interchangeable; different locking systems. The YC Onion does have a new locking foot pedal which I'll be recording an updated video during the NAB Show.