I admit to being a bit of a chilli head & prefer my sauces on the hot side. I have some Trinidad Scorpion & Fatalli plants on the go right now. Used in relatively small amount in a homemade sauce, "super hot " peppers impart excellent flavour with the heat. Too much heat ruins a hot sauce IMO, it prevents tasting anything after that.
The habanero is 250 - 450,000 scovilles & was for sometime known as the worlds hottest pepper - for good reason. The more recently found Bhut Jolokia, Naga Morich & Trinidad Scorpions routinely blow the 1,000,000 mark.
Sauces quoting more than a 1.2million scoville units are using pepper ( capsaicin ) concentrate like those used in pepper spray. These can be as high as 13 million scoville units & will apparently put a grizzly bear into a quandry. LOL