In reply to the.last.thesaurus:
As an habitual Guernsey wearer I can offer the following gems of info:-
Pros:-
They look smart when new.
They will save you loads of washing because they don't smell. I wear a Guernsey daily for work and wash it once every 6 months or so.
Proper Guernseys are made of worsted (long strand) wool which is pull-resistant, and the knit is relatively tight. It's not perfect, but it's not like a woman's fashion jumper which will snag on rough hands.
The wool is oiled and thus pretty much drizzle-proof. They don't get very wet when washed either.
The cut isn't restrictive at all - gusseted sleeves and some stretch sees to that. Don't forget, they were developed for fishermen, farmers and quarrymen, all very active jobs.
You can get them repaired if they wear out - it was common to have sleeves cut back and re-knitted when the elbows wore out. They take longer to wear out in the first place as there is no front and back.
Cons:-
Itchy. Not a problem if you can cope with it, or if you wear a long-sleeved shirt underneath them. You can buy non-itchy cotton ones but that defeats the object. Bulky compared to fleece. Need more care with washing and drying (handwash in techwash or soapflakes to avoid stripping the oil).
Caveat - I've not really climbed in mine, but I've done mountain stuff in them.
If you want the genuine article then you need to buy from Le Tricoteur, Guernsey Woollens, or Channel Jumper in Alderney. They're about £60.