I run trips over there and the season is great from July till mid October, earlier in the season the calves are smaller which can mean some really special images as the size difference is huge. Yes later in the season the calves are bigger and then can come close but it just depends. I know people who have had their best calf encounters in July, I am actually shooting for a big 3D project in July and then on my own trips in August / Sept as long as you are in the season you will have a great time.... no I should say a mind blowing time!
It is correct that you can only have 4 people and a guide in the water at one time but I have found that 8 is a good max number as it means that you get to get surface shots, relax, grab a coffee. It is reasonably physical getting so having a breather isn't a bad idea. I also find that in the group there are always people who are happy to sit out a couple of sessions so the keen people can get shots etc.
I have a couple spots left on my trips if you are keen, one on the first week and two on the second week, the details are here.
A couple of advantages of going with me are that I charter the vessel for the whole day not just 5-6 hours which the other operators do which means that we can leave early and return late if needs be to get the shots / time in the water everyone wants. I have never found people disappointed with the amount of time in the water they have had.... plus on our private charter it means we can go to a few out of the way locations.
No matter who you go with you will have a great time, do note though that Blue Lagoon gets booked very quickly. In fact I think they are pretty much full for 2013.
I teach this course at AFTRS (Australian Film Radio and Television School) based at Fox Studios in Sydney if you are ever over here. No teaching of dive skills purely underwater video and cinematography
Even if Dragon is released at NAB I'm sure it will take another 12months to actually get the upgrade. 2nd is that they have said that Scarlet cannot be upgraded but there will be a trade in scheme. However when looking at a camera that will likely cost around $28K minus trade in say $7k still $21K to find. Not pocket change.
I haven't watched all of it but the lines are probably due to the interlacing, options to solve this could be, download JS deinterlacer (free) and run it through that, I presume you shot 50i coming from the UK so export as 25p and try upper field first. anther option is to setup a 25p timeline and drop the footage into that and render and export as 25p.