I have a pair of Alturas and Mr Houtkop has a pair of Night Vision Alturas.
I haven't got wet yet using them, but they are too warm for summer use really (in summer unless you absolutely have to be dry; I find a better solution is to wear quick-drying normal trousers). I don't cycle as far as Shaun though - and I also don't cycle particularly hard, so I don't think I'll overheat in them in winter. They are supposed to be breathable etc etc but all the 'breathable' stuff I've got feels about as breathable as a plastic bag.
One point to note is that the legs on mine, and on Mr Houtkop's, are actually just too short (when sitting on the bike at any rate, your knees do shorten them quite a bit). Surely if you want overtrousers you want them to flap over your shoes a bit, not end mid-sock and then funnel water into your shoes? At the minute I've gotten around that by wearing mid-calf boots; but in summer it was right annoying. I'll get round to sewing on a 'frill' at some point.
(and I'm not the tallest of people!)