I have used 845 on my 93Galant which is outside 24/7; I iniitialy put it on in November, we're dealing with Midwest winters here, and it was still relatively effective the following April. It does seem as if the usual salt spray and other winter stuff washes off easier. It's great stuff; haven't tried the 476 but plan to...
The debate has always been that other premium products excell in shine or depth. Products that have to be renewed every 3 -4 weeks. I think much of that is real hair-splitting. I have P21 on my Miata now and the only reason it has lasted is that it's a garage queen. I do think the Collinite products are that holiest of Grails that everyone says they want but no one wants to beleive they can really exist---can't possibly be a substitute for their 87 coats of Zaino, NXT every month, or (can't say it with a straight face) Zymol.