has anybody else had problems with the montane jetstream, my rucksack has worn a patch and scuff marks on the back after just 4 1/2 miles, montane say you are not ment to wear a rucksack with this top

Hi Paul, I've not got a jetstream, but I've had a problem on a montane litespeed jacket when a buckle wore a thin patch on the front. It ended up being an old design of buckle with raised writing which acted as an abrasive (lowe alpine revised it to have recessed writing).
I do also use a montane aero windshirt though (same material as jetstream) and I'm not convinced that the montane shirts are as hardwearing as everyone makes out - I seem to constantly be repairing small holes in mine.
I've bought a fuera windshirt to wear this winter instead which should hopefully be a bit tougher, though I still think the montane shirts are a great item for summer - just not for constant use.

I've got the Montane Featherlite and it seems to be holding up very well. Used it loads over the last 12 months and only seen some slight wear and tear. Mind you my daysac shoulder straps are very well padded (Macpac Tekapo).

I reckon if you frequently carry a heavy sac then you'll wear thru eventually. My Montane Solo (2003) is showing its age a bit because i've used it a lot in colder months carrying a rucsac laden with extra kit.

I think that the lighter Pertex variants are fab for light duties but they have obvious limitations.