There's nothing wrong with cad red light, especially in a hot light studio setup. It's just a personal taste issue for me. When I see a red I want to splash around in it, so vermillion (mine is Michael Harding and - my opinion only - it is more manageable in mixtures than a cad red) is my attempt to stifle myself. (I just painted my bathroom vermillion, if you can believe it.)
A lot of my work lately has been in indoor natural light and I'm trying to get my color less flashy and concentrate more on other design elements of a painting.
I've got three reds on my palette at the moment - the vermillion, a transparent earth red and what is (probably) close to perylene red (a cool red, similar to alizarin but more permanent, right?) called "irgazine ruby". By the way,
Studio Products makes some truly wonderful reds well worth trying out. (That SP Vermillion looks great - anybody have some?)