I had an old (as in 10+ years old probably) Rab Vapour-Rise jacket in large which has been worn to death. The fit is great for me, really quite fitted around the torso but with enough room in the arms/shoulders.
I've just bought a new Rab Vapour-Rise Summit jacket to replace it in large (i.e. the same size) and it's way baggier around the middle. Previously I've tried Rab stuff in medium and it's always been just far too tight around the shoulders. Has the fit on Rab stuff changed over the years though, is it now generally baggier and less athletically cut?
Clothing (especially letter sizing) is a lot like IQ. A medium is a medium and 100 is the median but what that actually means has become something different over the years, to the point that a Large from 10-20 years ago is something different than the Large being produced currently. People have been getting bigger - not in the least around the belly.
So I'd give the Mediums another go but it might also be that Rab has tweaked their fit somewhat to appeal to a broader (ie. less athletic) audience. Otherwise give Mountain Equipment a go. Some of their items have a decidedly trim fit.
I have the VR summit in a medium...great jacket but I would prefer it a little slimmer cut. I'm a slim 6'2".
Agree the other poster that ME gear is generally longer in the torso and slimmer cut and I'll be sticking to their stuff in future. Not that the Rab is a bad fit....just ME is a bit better for a string bean like me.
The oldest Rab stuff I have is from maybe 10/11 years ago and I've always found it as you describe the newer stuff. Seemingly made for people with long, slim arms and bulbous guts- nothing like you'd expect of a climber.
But come to think of it, my older jacket, smock and windshirt needed to be XXL to fit my chest and arms (for bulk rather than length) but 2 newer fleeces XL was fine.