Have noticed that they hardly ever get mentioned in the numerous 'What tyre?' threads.
I've used them for two or three years now - bit draggy and slow rolling but fantastic grip on all surfaces, secure when cranked over, never pinch flat and seem to last OK. Even shed mud respectably.
Folding ones don't seem too heavy.
Used on a steel hardtail with Mavic 719's. Mostly 2.1's but have just stuck a 2.25 on the front for 'Summer'.
Anyone else use them?