I bought a PowerPro headstock but my old headstock (1992) is in great condition and been well maintained so I couldn't just get rid of it, plus I have other attachments that would be handy to be powered up separately. I was looking at the shop deputy, but I found an entire main frame on e-bay for a little less. One thing leads to another. So naturally I bought another carriage and a main table for a 510, then an extension table that came with the tubes, two floating tables and telescoping legs. Now I have basically two 510s sharing the miter gauge and fence.
I've been pondering upgrading one to a 520 but not sure if it is worth the cost.
I've been happy with the accuracy of my 510.