I also use Schmetz a lot and they fit with most domestic machines...as for different needles for different purposes (some of you mentioned this) many quilters are now using topstitch needles for all aspects of quilting and for every type of machine thread used in quilting. The topstitch needles have a larger eye and larger groove along the top of the needle with a sharp point so they accommodate all types of threads, metallics, rayon, etc. For those who use all topstitch needles, they do use three different sizes depending on the size of thread they're using (eg, 8, 12 and 16).
Superior threads now sells their own brand of needle made by Organ and the Topstitch needle is the only one they sell (in three sizes). Their needle is platinum coated to lengthen the life. and no, I don't work for them or hold stock in the company 8-)
Using the same type of needle on all quilting means, to me, that I save money because I don't need to buy separate speciality needles such as metallic, quilting, topstitch, etc. I suppose there may be some really unique stitching in non-quilting activities that might require some special feet but since I rarely go there, I don't worry about it.