I've had a Flux for years now and it does pretty much exactly what it says on the tin. That said, if I were to buy again now, I'd probably take a look at the ME Fitzroy for fit (and a teeny bit of brand loyalty) reasons.
Had a Flux, didn't find it that warm. I sold mine in the end as I preferred my Karrimor Avalanche, a 40quid Primaloft filled bargain, though the hood wasn't as good.
Since then I've bought a Rab Generator Alpine (solid jacket, sized well for chucking over everything) and a Patagonia DAS (just okay- not sized well for a belay layer, elastic cuffs I don't like, but a good array of pockets).
I'd buy a ME Fitzroy if I could justify another jacket or needed to replace the Rab.