One of nicest hidden gems in Windows 7 is exFAT. It's a simple file system with support for huge files (16 EB) but without any support for access control. Pretty straightforward replacement for FAT32.
As leap of faith action I decided to format one whole disk with it. It was disk that kept my multimedia files and occasional virtual disk. I wasn't troubled by security since BitLocker works like a charm even inside of VHD. Unfortunately that plan was snipped in the bud.
As soon as I created virtual disk I was greeted with "The requested operation cannot be completed due to file system limitation". Even worse, you cannot attach already existing VHD that happens to be there. It simply refuses to do anything.
While I haven't done any detailed analysis, it seems that exFAT and VHD do not work together.