Wouldn't there be a problem with vendor support? Presumedly you'd have something in the contract where they'd fix things that break when it's their fault. That would include hardware and firmware. For the later, they might just insist that remote access is the only way they can fix it. If you need to upgrade the firmware then you need to do the audit all over again. Maybe an open source firmware would help, but at the end of the day you still need a vendor you can trust.