No reason for the VFD's as of yet. These units are large and are for very, very large residences. I think that since money is no object they use VFD's as a selling point instead of relying on the on/off staging. Right now there are two fans per circuit on this unit. I haven't heard if they want a VFD for each fan or one VFD with two fans.
A P66 speed control on the lead fan should give them what I 'think' they want and it is for single phase fans. It may just be a case of the sales to customer link not realizing the difference between variable frequency and variable speed.
