Yes crumpton could do better. Fully geared is a stretch at best. Thats a vintage Huret Derailleur which probably works but light parts like that come with huge sacrifices. The Ghisallo frame has a reputed crap ride. Stiffness info includes the stupidly flexy headtube junction. not fun. Crumpton's frame would presumably be stiff at least.

Rue has just made a 600g frame too.