Keeping on the subject of weight I do feel even in the red sea you do not need a lot of weight, (I have also used a dry suit in the red sea with the same weight on Duxys winter warmer).
For example here is a long exposure image taken in january of this year, http://wetpixel.com/...=49820&p=347899 what makes it stand out for me is the fact that i did twelve exposures with the gel on the torch with just 4Kg on me on one dive and at no point was i "floating of to the surface".
In true goose style i forgot to bring down the pre made weight belt for the tripod, and in turn i then at 15m had no choice than to pull out a weight pocket to sort out the tripod issue:
In fact setting a shot up like this i had to:-
* Set the timer on the camera to approx 20 seconds delay.
* Fin like a mad man being very careful not to kick up the sand to the starting point to the left of the image.
* Once the timer had finished and start of the exposure then follow the contour of the rocks and in turn switching of and on of the torch and continuing the shot to the end of the 30 second exposure.
* Finning back to the camera to check the exposure and make any adjustments to the image.
* Repeat 12 times.
In short i could never have done this image on eight Kilos and I'm glad i forgot my weight belt as it also taught me you don't need loads of weight when diving and the dive guides are right.
The difference between a self Isolation between a trilaminate and a 4.5mm neoprene dry suit is negligible as I've worn both with the same under suit and found no extra weight is needed. I will say that my ankle weights do come in handy when my mates forgot to put his weight belt on. lol
My Kit:- NikonD800 Nikon D90 Nikon Prime 105mm & 60mm macro, Sigma 15mm Nikon 16-35mm Nikon 12-24mm wide angle, Tokina 10-17mm (the tit's of a lens) Nauticam NA-800 Aqutica AD90 housing, coupled with X2 Z240 mofo strobes G.S.E. 360 Ring Flash.