Dear Sir,
On the KC705, Xilinx decided to not route HPC connector's bank HB. Therefore it is not compliant to Vita. As per the Vita specification, a full blown HPC FMC connector requires all the bank to be routed to the CPU/FPGA (HA, LA and HB).
FMC700 does provide a fully HA, HB and LA using both LPC and HPC connectors on the KC705.
FMC-HPC has many pin and you need an FPGA with a lot of IOs to have everything connected and typically the FPGA on the KC705 is an FPGA without much IO/s.
I hope that helps!
Best Regards,
Arnaud