If going for very light stuff, check it's specs -IME you don't want to be using calendared (cired) or downproof fabrics like Impetus or pertex for an inner tent (unless having a good area of netting too). -CFM will likely be low leading to possible condensation issues. The tent inner is so far away from a heat source compared to clothing,a bivi or sleepingbag, that condensation may occur inside it.
An acquaintance who made an inner from pertex for his Golite SL3 encountered very poor condensation inside the inner when tested.
Also, I see these half solid/half net inners with sil or cuben for the solid rather than a breathable fabric. A friend has one for his Trailstar – and really wishes he hadn't – condensation above face and on feet!
How about this stuff Peter? Yellow, similar to the Hilleberg and Terra Nova Inner fabrics (40gsm =1.2oz/yd)
http://www.extremtextil.de/catalog/Ripstop-Nylon-impregnated-inner-tent-40-g-sqm::1972.html