A bit tricky this one.
Most comfortable of all is undoubtedly normal good outdoor clothing with synthetic base layers. In clement weather you can go for a swim, warm up and keep paddling in the same wicking layers. The trouble is, if you flip in cold nasty conditions, you need to get to shore, dry out, warm up, put on your spare dry clothing - then what do you do if you flip again (in the same nasty conditions)?; you are out of options and all your clothing is wet.
I have enjoyed paddling in a Farmer John wetsuit (no arms) and find it a good combo with (say) a fleece over the top keeping your arms warm. Absolutely no chafing. However, they do act like a neoprene wine cooler when wet when you are out of the water and back in your boat.
Dry trousers are excellent garments in their own right and are nice to paddle in, keeping your legs dry when wading, sitting in a half-swamped boat or getting in and out in waves. In my view that is what they are for. Dry-trousers are best without socks for the reason given below.
I tried combining a dry-top and dry-trousers to make a versatile dry-suit, and wouldn't recommend it. The combo leaks at the waist, slowly or quickly depending on what you have, and the trousers get heavy with water inside them, which makes getting out of the water difficult.
For deep cold nasty water and white water I now prefer a dry-suit. I would count any Scottish loch in that category if there are wind and waves. You will stay dry in dry-suit. However you will also get sweaty if you run around on shore too much and you can get cold inside a dry-suit without enough under layers, especially your feet. Alternatively you can boil in the bag. However, for that feeling of confidence I always have my dry-suit with me on a multi-day trip now.
No perfect answer as always, just my views
Last edited by Perthshire Wood Canvas; 29th-April-2012 at 03:17 PM.
Know less, carry more - you're in a canoe !