I use Oxford Drybone muffs, they take 2 mins to fit or remove (allow 5 for the first couple of times fitting till u get used to it)
100% water proof and wind proof so far, they have a ridged leading edge to stop them folding in at higher speeds. i find them fine to around 100+ then they do tend to start to fold in a little.
i belive nooj is doing a bulk buy deal in forsale right now on muffs. i havent used them so cant say how they are, but knowing nooj they will be of a good quality.
as for glove linners i use Chill Out inner gloves, very warm and wind proof. also use a chillout neck and chest guard. then have Cold killers legs, boot inners and shirt. got a good deal for the set at NEC on the weekend. again very warm and wind proof.
i do belive in being warm when riding in the winter. if your cold then your not paying attention to the road.
As for crashing in the muffs i wouldnt think they actualy give much if any protection. but then i am wearing my summer gloves under them so they would be my protection. I dont feel they would be in the way if i came off.