Isn't the JVC
HM-DH30000 capable of recording HD component video? I don't believe you need to convert it to IEEE1994 to be able to record the HD signal.
Be careful about IEEE1994, firewire, i.link because it only specifies the physical interface. The JVC, for example, accepts DV encoded and MPEG2 encoded video, but outputs only MPEG2 on the IEEE1994 interface. Recently, some Sony camcorders are using MicroMV format which MPEG2, but I am not sure whether it is compatible with JVC's MPEG2.