In reply to Souljah:
I suppose it depends on how much you're going to be using it. What you're going to be using it for and how much you're willing to spend. I had a kag in a bag type thing which I found to not breathe at all. You could go for a Craghoppers Pakka jacket:
http://www.completeoutdoors.co.uk/product_info.php?products_id=1898
I would suggest they are more summer/light shower solutions though. At this time of year your best to go for something a bit more sturdy. I spent about £90 on various lightweight jackets and was never happy until I decided to splash on the ME LHotse.
If you're talking about the Rab jacket being a tad too much for the Scottish winter then I cannot comment other than saying that from what I know Rab gear is very high quality.
If you want a jacket you can use to do the Munros in/hike in all year round in the UK then you will want something without too much built-in insulation (fleece underneath for winter) and HIGHLY waterproof. i.e. the ME LHotse or similar.
If you want a winter jacket to say stand about belaying 900m up a hill in a blizzard when your partner is leading an ice pitch then you will probably be better to go with something with in-built insulation AND wearing a fleece underneath it...
Ands