Hi,
Right, should've clarified -- the LED device in the hotshoe will be TTL. The Sea & Sea literature explicitly pushes its compatibility with their YS-110's TTL slave system. Cool stuff...
And with Inon D2000 and Z240 ?
Is this new camera work well without the LED accessory.
I hope that better than compatibilty with the YZ-110 
Because in S-TTL this function is not useful.
... Dave, you misunderstand the issue with slow recycling. It's not the external strobe that you're waiting for - it's the camera's built-in flash that takes so long. Since the built-in flash is generally blocked and/or too weak to reach the subject, the camera will choose to dump its full power with essentially every shot. Not only does that kill your shot-to-shot time, it drains the camera's battery faster....
Normaly in S-TTL the internal flash don't dump full power.
The problem exist in manual mode, for exemple in Canon Powershot camera, the trick's in doing reduce the manual power of internal strob. It's possible.
But if this option don't increase the price, why not.
Otherwise, I am very interested by this camera. It come up my expectations.
Greeting
fp
You can read a french review of Inon S-TTL system on my web site :
http://www.fplanglois.com/plongee/technique/inon_sttl.php
Sorry for my bad english, I am froggy (but I have my head examined
)