In reply to sor1n3l:
I've been climbing on mountain crags with a pal wearing a sailing jacket and he survived. However, that one looks neither that waterproof nor that breathable. So it might be tough, but compared to a decent mountain waterproof it'll be a bit boil-in-the-bag. It's also telling that they provide no weight figure: that's not an issue if you're in a boat, but clearly a consideration for walking or climbing.
That Musto jacket has a hydrostatic head of 5000mm and a moisture vapour transmission of 3000g/m2. Fine if you're standing in a boat, but very unimpressive compared to the stats claimed by outdoor gear brands. Highly breathable outdoor shells can have 20,000mm of waterproofness and breathability figures (at least on paper) up as high as 50,000g/m2 or more...
For mountain use the ability to attach a fleece is basically redundant: you're more flexible being able to put on and take off your insulation and shell layer separate to one another. Again, sailing is a bit different in that regard perhaps.
Finally the cut: it is unlikely to be articulated enough in the sleeves and/or long enough in the hem to let you wave your arms above your head all day and stay put under a harness. That's not really in its remit.
Personally I'd buy a tough mountain shell for mountains, and also then wear it in the boat. But the decision really rests on how much of each activity you do relative to the other.