I have also been thinking these choices a lot and ended up finally to good quality CF sunroof replace part from Getty Design. Priced $250. Nowadays dollars are also very cheap compared to euros..
That sunroof part area is almost 1/2 of whole roof and then I don't have to install (heavyweight) roll cage/bar. So weight advantage is still maximum..

and what comes to that sunroof pulling out question, that is propably because there are so much air coming through the front cold air ventilation at those speeds..
Cure for that would be a flat hood..
or "scotch tape"

 

With yesterday's fun and games I've confirmed that air pressure inside the car drops at speed so there must be a low pressure area over the sunroof after the airflow gets deflected by the windscreen and comes over the roof. That increased slope windscreen should help!

 

Ok, then my idea was wrong. Would be nice to see if somebody glues little narrow and long scarves to top and front area of the roof and then this would be videotaped at high speed (=homemade windtunnel). Maybe this lifting effect can be seen then?

But what comes to that "big" front cold air ventilation opening. Maybe would be beneficial for high speed driving if that are taped to closed up. Has anybody tested that point?

 

Well I did at the 11/11 Vmax, as mentioned on the other thread, and my sunroof didn't do a James Bond/MOD500 liftoff thing. But it didn't do it without the tape either. Phelix and I both noticed our sunroofs seemed to be sitting a little proud of the roof and Alan thought it might be caused by air entering through the hood opening and looking for an exit via the sunroof. He suggested the tape. It certainly provided some confidence and did no harm, but Phelix's subsequent testing would seem to negate this theory.