I don't know about noise and all that, but I have the 16x slot load version and have no regrets. It just seems to me to be much more convenient and "slick-er" to have the slot load as opposed to the clumsy tray loader.
Some have noted that the slot loader cannot accept the smaller CDROMS, but to date I have not yet come into contact with a small CDROM, so it doesn't affect me as I am sure others as well. Go for the slot load, you will surely have no regrets!