Has anybody synched the XH-G1 with an XL-H1?
 

I connected an XL-H1 to an XH-G1 via SDI cable from the Timecode sync jacks and the two cameras locked. I then disconnected the cable and the XH-G1 was still timecode synched to the XL-H1. If I powered off the XH-G1 and powered it back on, or, even if I removed and reinserted the battery in the XH-G1 it still remained in synch with the XL-H1. The XH-G1 was behaving as though it had defaulted to free-run mode.

Has anybody else tried this?

That's normal. Once you connect the two cameras, they remain in sync even after they are disconnected (although there may be some slight drift over a long period of time).

It would have to be in Free Run in order to sync in the first place. The menu controls the type of timecode the camera produces. The camera timecode type is not controlled by connecting or disconnecting the cable. The cable only provides the numbers which the camera reads if it senses a proper signal.

I've tried flash-syncing an XH-G1 & 2XL-H1s on free-run time code and they all drifted off from each other in less than an hour.

Timecode synchronization of XH-G1 to XL-H1
 

Actually, the XH-G1 automatically went into free run mode after the timecode sync SDI cable was connected and the two cameras locked. It had NOT been set up this way in the menu prior to being connected to the XL-H1. It had been set up in rec run. So to clarify, your assumptions are untrue.