clothing for fastnet

My experience also - I have a pair of fairly porous breathable hightops.  Replaced with Gill ones which cost a bit more but seem to be much better value.

My XM kit seemed like a good buy at the time but has unfortunately turned out to only be worth what I paid for.

I also would say that a smock offers greater manouevrability than a jacket.

Tastes vary but for offshore racing I like a jacket with life-jacket already attached, so you put both on with one movement. It means a bit less messing about when you are getting up in the dark to go on watch, possibly feeling a little rough until you are out in the fresh air. I have never tried it but I can't imagine that working with a smock. You can remove the life-jacket for inshore racing.

Depends to some extent what job you are doing on the boat. If you will be bow or mast, an "Ocean" jacket will keep you drier. If you are a trimmer or helm, you may find something a little lighter and less restricting of visibility is better in all but the worst conditions. That's my view anyway - and I've done several Fastnets.