Hi guys...Ill get some into try now that its easily available, but do you find that 400 twill is twice as strong as two 200 twill layers. I'm hoping its just as drapeable and the weave is more stable than the 200 twills.
Cheers...Chris

In terms of stability, a 240/245g twill is usually much more stable than 200g. 

It's usually more tightly woven and the added expense is usually worth it where cosmetic appearance is important.