I've got several different Tobasco sauces in the larder, one of which has a 'fiery' red and orange label. I agree that it doesn't have the best flavour to taste ratio, so I often combine it with other random Tesco bought stuff (Jaimaican sauces and the like).
The hottest I have ever had is Blair's Mega Death Sauce, and only because a co-worker dared me to. He practically drinks the stuff, but then I have my suspcicions that he is in fact clinically insane. I would perhaps use maybe a few drops for a whole saucepan of regular sauce.
I do enjoy a nice curry though, which is what I had last night. I only had a mild Tikka Masala this time, which was lovely.