Hi Carl, I photograph primarily in B&W and children to earn a living and have a 501c/m and am about to purchase a 500c/m as well. I've worked with both and really love them. I'm not trying a 503 or others that come with a higher price tag as the 501 & 500 do the job and with incredible results. My 35mm rarely gets a roll these days. I don't do studio work or weddings but find myself chasing moving targets most days and have learnt how to handhold and work the blads very quickly - with lots of practice. Good luck with your decision Carl, I'm sure you love it.
Kind regards, Nicole