Ended up going with a standard 3/32" KMC 9-speed chain that I got free from CRC when they sent me 2 last year... it was 115g lighter than the 1/8" SS chain I originally had on it... granted, some of the weight saved was down to it being shorter. Also saved 44g going from the 39T BMX chainring up front to an FSA 34T, and another 17g at the rear (going from 19T to 17T Surly cog).
I do like it when retro and lightweight come together... 124g for that Ritchey Prolite WCS bar is verging on the ridiculous.
Already thinking about what I'll change on the Fat after Dunkers... Popping the wide bars back on is a definite, that'll probably cost me 200-ish grams. And I'll put the Turbo back on it, looks wise I think it's preferable to the Flite (+ 90g) - I suspect my arse will prefer it too. The Mythos skinwalls will stay, since they look good but not really all that keen on them grip wise.