Hi lou!
I've been to Marsa Shagra for the second time now this May and pretty much hope to be returning there this October again...
The tents are the best option I believe, all you want above your head in that heat is a piece of canvas
You just flip it's enterance up the top and it vents quite well. I've been to one of the huts for a visit, well, I prefer the tent (have no info on the A/C-d chalets, but they are more expensive and hey, where's the magic of the desert then
). The sea is just a few meters off the tent area, cool...
The bathrooms are cleaned often, there is always someone to tidy up things (it seems that there is always someone around for any task, lots of people work there)
New to the grounds is a great restaurant building (with A/C) and cool terases to overlook the sea... (Last October there was only a straw-topped area with plastic chairs - I liked it as well)
The house reef is cool, both North and South provide nice marine life. You dive as much as You can and want, one can choose between various options of shorediving, zodiacing or the mix of the two...
If You have time, do visit Shaab Abu Dabbab and Sharm Abu Dabbab, one is a huge coral garden with barracudas at times, the other is a complex sytem of caves and caverns, coool. Nemo city is also a nice spot, I'll not give further info on that, guess...
Baseem Mohammed was our guide the last time, I'd happily choose him again.
Regarding security, we were a group of photographers with lot's of gear, laptops and stuff and everything was safe in the tents and in the pools of the divecenter. It was usualy loaded with cameras, lot's of people come here to shoot (judging from the stuff I've seen in those pools).
Here's a link to the gallery of the visit in May, and here You'll find last Octobers pictures...
Hope I could help, have a nice time!
Zook