Good points and info thanks Mike - I suppose most light weight gear is going to sacrifice some durability, but I don't want to spend money on something that is only going to last a season. I've read lots about the Montbell jacket and people seem to have had many years use out of those and still getting use out of them.

I have a rab generator jacket, its lighter than my fleece+go lite windproof but warmer, it is quite delicate though, i have holes in all the pockets and its relatively new, would be looking for something a little more robust if i had known in advance.
andy

I noticed a Chris Knapton idea where he bought some cheap polyester wadding, cut a hole for his head, and simply wears it under his windproof:
apparently cheap lightweight quick drying and effective!!

Link to his instructions

Hi you might consider OR jackets. Cameron McNeish praised the Outdoor Research Fraction Hoody in one of his articles. I tracked it down to 'CountrySide' store in Stevenage and tried it on. It has a hood and is a bit heavy for you perhaps at about 460g. However there is a version of it called the Neuplume(?) which doesn't have a hood. I think that comes in about 380g. I found the neck a better fit on that than on the Fraction Hoody.

My experience is that insulated tops are too warm for walking in. Also most use a nylon based outer fabric which provides durability but NOT breathablity. The result is that after ascents my jacket can get wet with sweat and take hours to dry out. I have a Patagonia Zephyr and Montane Krypton(?) which use a microfleece lined nylon shell. With the right base layer I can use the Montane down to -6C maybe -8C as long as I'm active! If you sweat a lot I'd recommend a Pertex outer if you must go for an insulated jacket. I have a Moonstone jacket which uses Primaloft for insulation and despite getting damp with sweat on a climb up Helvellyn it still kept me toasty warm in a temperature of -21C with the max. windchill. It has a nylon shell and is no longer manufactured as the company went bust.

Also watch the weights of Primaloft insulation. The Montane Fireball uses just 40g insulation and comes in around 280g in total. After that most use 60g of Primaloft and then some use 100g Primaloft on the body and 60g in the arms. Some go to 130g insulation and some as high as 170g for mountain belay jackets. Try tracking down the Montane Fireball if you can.

I dont know where you live but the TOG24 outlet store in Clarks Village in Street are selling jackets with a Dupont fill for less than 40£. The loft is nowhere near as generouse as primaloft 1 but its similar to primaloft eco. Weighs about 500gms. Fits well either under or over my Paramo smock. Certainly warmer than fleece of similar weight. Nice warm pockets simple inner pocket hem draw strings and a dropped tail. Practical and cheap. If you need more warmth Paramo make a primaloft 1 filled one wich looks almost as lofty as down, problem with the super lofty stuff is that if you wore it under a waterproof you would compress the jacket so you might well have bought a less lofty one?
Andy

Patagonia Nano Puff would be my suggestion. Amazingly warm, light and versatile.