Epoxy system preferences?

Yes its a real sod that you have to put all that stuff in the msds - it makes it easy for others to pick apart your systems without them even having to do any real chemistry,( like sticking it through the gc or ftir,) but then I have got quite a bit over the years from the msds 's of others, even though sometimes you suspect that they have the odd porkies in them!

I do umpteen mixes in a week, and it's very very rare to get a soft cure  -  weighing - kitchen scales are good for mixes  30g  - 2 kg.  Pumps get gunked up, and don't measure accurately , so i use the big pumps for R and H just to get it out of the containers, but weigh everything.
e g for 320 - weigh resin , subtract 8g cup weight,  times 4, divide by three, add 8g = weight target with hardener.
I always have several kg of either resin or hardener left when it's time to buy more, so it's good to keep with the same system!
I think west 105, SP106, sicomin 5500 are very similar.
SP 320 is a bit thinner and flows better, maybe better properties. Fast cure even with slow H.
Sicomin SR8500 is thicker but is good when vaccing, fast H is relatively slow, and has good performance when cured at ~ 60°C

320 is not just clearer 106 -it is a completely different animal. 320 is generally a higher spec system. I would go for what Andy says, he knows, as he has worked with most of the systems (- I just formulated them.)

Lot's of very useful comments and advice, thanks! The brief response is that I guess I will be contacting Matrix for detailed advice and materials for our build.

I've used West by volume and by weight with no difference in terms of the results. The biggest issue is always amine blush but if using it as an adhesive with low density filler this doesn't usually present a problem. If you do use West, I'd recommend using 207 hardener (for clear coating). Once you've cut all your panels out, roller it on all surfaces. The only bit of the West system I've been disappointed with is the filleting blend which used to give a nice orange wood colour but now seems a bit beige.
In the Grad fleet they were quick to make use of West in the mid 80s and these have proven to be some of the most robust long lived competitive boats in the fleet.

I have used Sicomin resins when we built the C-class Invictus, but this was exclusively with Carbon rather than wood!!!!! Found it to mix out well and cure consistently. Wiz is always full of good advice and will make sure you get the right stuff, but I found it a bit pricey.

I've never used SP so can't comment on it.