Like many, I use my colour head for filtering - and yes, it is, if anything, a little more fiddly than using filters. I don't have the skills to ensure all my negs are exposed and developed for the conditions to allow me to use only grade 2 paper (although I do try...).
I also like to muck about, trying different contrasts for an image amongst other things but if you have a standard look in mind and have developed the skills, it must save you time.
I hacked my Durst L1200 Lab. head to allow me to switch between full Yellow and Magenta with a switch to make split-grade exposures simpler.
I don't believe the contrast will change between different light sources using an incandescent lamp - but I believe older cold-light heads were often bluer which may move the print to a higher contrast. Ilford multigrade data sheet here (
http://www.ilfordphoto.com/Webfiles/...0201152306.pdf) has something to say on this.