In reply to JIMBO:
Never quite as simple as one move to another as the same route may have several viable crux sequences and maybe use different holds.
It always struck me as one of the more obvious difficulties of the tech grade in that it relied on people agreeing what constituted a move.
Indeed some routes I've done have alternative sequences that are individually easier but take longer meaning that some people prefer to do a harder single move instead of a sequence of slightly easier ones to the same end. What would be the tech grade then: the harder single move that most do or the easier moves that only stamina weaklings like me would do to avoid having to pull hard?
There's no real answer to this because I think it's fundamentally impossible to identify a single agreed hardest necessary move on many routes. Somehow the tech grade is still useful in spite of this - I suppose because most routes will be climbed roughly the same way by most people - but I still think that a Font grade is conceptually more useful.