I found a screenshot on my desktop of a short experiment I did with these modules a while back.
It was a quick and dirty test, but I thought I'd share it here...
I simply connected sender and receiver module to 2 gpio's (one for sending, one for receiving the signal) on the same axoloti. The sender and receiver were approximately 1m apart.
The maximum send rate (at which all signals seemed to arrive) appeared to be 2.29Hz.
The latency that I measured was 64.79ms.
So: for clock signals this path is clearly not usable (as probably most of you might have guessed;-). But it could be an interesting technique for art installations etc where latency of around 65ms is acceptable and you need to remotely control lamps, motors etc...