The advantage of the SP-3A1 and SP3C are of course the tone controls if you require them. Hands down the SP-3C sounds superior to the SP-3A1 in tonality as well as quietness, detail etc. Basically there was no downside to the power supply update. The SP-16 sonically represents more closely current production ARC product. I have not heard the SP-16 side by side with the SP-3C. I own an SP-3C and won't sell it. I love it. It is a bit more tube like and a bit more romantic and probably not as quiet as the SP-16. And of course, the SP-3C has no remote.
