Would your "system" work well with:
First of all the system isn't mine and I can't lay claim to being that smart as to see the obvious, this is the way some clever bloke in the army decided it should work and I have just been pointing out that this scheme also works well for stalking etc. Not only is it the best solution for our climate where you can have hot sun and hail all in 5 minutes but it is cheap as well.
I have worn windproof fleece jackets under various non-waterproof shells for a long time now and I would sometimes wear one with my windproof smock. Now it is important to realise that as neither layer is 100% waterproof so the final solution will never ben 100% waterproof however as with the smock you can also wash waterproofing into a fleece jacket and my experience has been that this works very well. The truth is that for most purposes it will be more waterproof than you need for most stalking.
The down side to wearing a windproof fleece under the smock is that the fleece has a lining which is not as breathable as the smock will be so it will tend to sweat you a bit more, often the windproof layer used is exactly the same material as used for waterproofing (i.e. Teflon type stuff) so you could expect to retain moisture in a similar way to when wearing a Gore-Tex layer, in fact the only reason why it isn't sold as waterproof is probably because the seams aren't taped etc. So in that respect you abandon some of the advantage of having the very breathable windproof smock but this will only be a problem if you don't keep it in mind and use your common sense when out and about.
As with the Gore-Tex layer designed to be worn under the windproof smock it is probably best to put the fleece on only when you need it so ensuring maximum breathability. If you walk hard in a heavy fleece then you will get damp no matter what the weather. I know that sounds like stating the obvious but you'd be surprised at how many people spend £1000+ on the latest waterproof gear, climb a hill in it and then want to know why they are wet when they get to the top.
Be careful of some of the "SAS" smocks as, clearly, this is only a marketing claim aimed at bumping the price up and even with a genuine Para or SAS one the only difference is often an extra pocket, or different cuff material. You can get the standard British DPM smock for £10 so if the smock you have ordered doesn't suit you or isn't as water repellent as you'd hoped pick one up and give it a try though I'm guessing you are trying to avoid the cammo colour scheme.
Another point to note if you don't like the cammo thing is that the desert windproof smocks have a light beige/brown colour scheme and some people have success dying them brown so the beige bit effectively darkens to match the brown bits. The result isn't completely perfect as you can usually see darker and lighter areas if you look closely but it might suit your purposes. Again the desert cammo smocks are very inexpensive.
