Before I had my GS, I bought a Hein Gericke Tuareg suit. I am very pleased with it - take the lining out and undo the vent zips and it is very cool (not hot as opposed to trendy) for summer use. With the lining in it is 100% waterproof, but can still be cool and waterproof at the same time.
It isn't a full-on winter jacket - I have a Richa Eagle jacket for really cold days - but it is very versatile and perfect for the other three seasons.
Trousers are a funny low-waisted fit, and it does get grubby quickly, but that adds to the hard man overlander look (well, I think so!).
Robin.