Hi Mario1976,
Thank you very much for the update. I use the ESXi free edition on my server at home and unfortunately I don't have a support contract to log this issue. Main reason I'm using USB DirectPath passthrough is because I've got a virtualised MediaPortal TV Server with a number of USB tuners, and performance/reliability is a lot better in this mode rather than using individual USB device passthrough. As you say, at least it works for one reboot with ESXi 5.1 build 1021289. Hopefully the guys at VMware will make this a supported feature as it is definitely very useful for a number of reasons.