I realise that this is a 'how long is a piece of string' type question, but here goes...
Having had a slightly hairy recovery on a slip I had not used before (I love the smell of clutch material in the morning

), I was wondering how other people assess the suitability of a slip before getting to the point of no return?
Boatlaunch is a help - if it says steep slip or 4x4 only I know to avoid it. My car's manual (manual Astra 1.7 diesel) specifies maximum incline of 12% when towing - does this sound like a useful guide, or is it likely to be over cautious?
Any thoughts / opinions?
Cheers
Chris