Hi Stu,
>> So is this more of a debugging tool?
yes sort of debugging, but perhaps sort of "prevention" as well. As long as it doesn't interfere (ie isn't visible most of the time) it's a useful thing to have on because it alerts you to problems immediately. Certainly having it on during development is good.
I usually deploy with it in, and then once the deployment is tested, turn it off. In NT8 the setting is now an expression, so you could deploy with it on to check that everything is ok, then just adjust a setting on the server to turn it off.
>> (am assuming that if we turn it off in the template, then we'd still be able to use firebug etc to debug)
absolutely - it doesn't affect firebug - actually it's more of a hint to go look in firebug to see what's wrong.
cheers
Bruce