It's worth noting that this is unnecessary for iOS devices, where plugging your device into an unknown USB port prompts you to either "trust" or "not trust" the computer in question (with "not trust" disabling data transfer).
Do you trust your "trust" and "not trust" settings? Are you sure that there are no backdoors in there, or bugs that could still lead to device getting hacked?
Honestly? No. There's a bit too much electronics in that one for my taste. I'd happily trust the one designs of which I audited, and board I soldered myself. But until I get over to doing this, I'll be stuck with just cutting data wires.
EDIT: I retract that. From what I can tell, it's just three SMT resistors on that board. So it seems fine to me.
knowing how well apple does embedded security, there's probably a vulnerability that'll allow bypass of that feature - it's just a matter of how long you want to invest in finding it.
Most iOS jailbreaks have required a USB connection, so it seems the USB port was/is an attack surface. I haven't looked at the individual exploits used in each jailbreak, though.
It's been a while since I looked at it, but they were often used to get the phone into DFU mode and upload data that way. Seeing as DFU mode requires the phone itself to be rebooted, you'd likely notice what was going on unless you left it unattended.