Hi John,
Good timing as I am just back from Thailand.
First of all, some good news on the luggage allowances. None of us had any problem with luggage. Half of us flew Thai, half BA (but with Thai internal flights). I was on BA so actually took two housings and three subtronics and was still way under weight. Of course, you may have to take test gear. But I guess I am saying I would not expect the baggage to be a problem.
Regarding the Inons. They are great guns. Very powerful and mine have been 100% reliable. Quite a shock to the system, that last point. Yes - one of my Subtronics re-developed its old fault in Thailand. Just back from service too. What a shock. Not. It is always the same one and it is always the same fault!
Sorry, keep getting distracted. I always use the Inons with the 0.5 diffusers on them. I use 2300 batteries - which I find last three dives. I generally use power settings a couple of clicks back from full. Wide angle positioning same as Subtronics. Macro positioning there is more flexibility because of their small size. Although I doubt you will shoot much macro.
The Sea & Sea cables are not as confidence inspiring as the Subtronics. But they are fine - plus more reliable fit than on Sea & Sea's own strobes because of the machined instead of moulded connector on the strobes. But with only 1 o-ring rather than 3 they need to be checked more than the subtronic ones.
Hope that this helps,
Alex