I'm skeptical about using any head that would mount the C6 on top rather than on the side. These photo heads are not designed for pointing the load straight up.
Since you already have the 502AH, it wouldn't hurt to try it. You'll realize if it's a bad setup if you need to lock down the altitude detention every time you point toward zenith.
My 501HDV fluid head has an advertised 13.2 lb LC. It is OK for the C90 and borderline for the C5. I would not even try it for the C6. The MicroStar works great for the C5 and C6.
I've used my C6 on top of a 501HDV and it worked fairly well. Yes, I had to tighten the altitude tension knob, but it was still acceptable as a grab and go setup. Having said that, I prefer my Stellarvue M2 alt/az mount over the Bogen head.
Yes, I recall seeing your pics of this setup. I think whether or not the user considers it "acceptable as a grab and go setup" would depend on what they consider "worked fairly well" means.
I've had my C5 on a 501HDV and also 25x100 binos. I definitely had to tighten down firmly on the altitude tension knob when going near zenith. It did not instill confidence, and it was a bother having to keep adjusting the tension knob. I tend to go all over the sky during an observing session, so it was a real bother to me. I imagine mounting a C6 on the 501HDV would be even worse.
A head - like the DwarfStar, MicroStar or M2 - which hangs the scope on the side will be inherently more stable than one which mounts it on the top. The MicroStar is just about right for the C6. The DwarfStar is a little too small. It's better for a C90. The M2 is beefy enough for my SW120ED or EdgeHD 8".
Edited by Sarkikos, 29 December 2016 - 06:38 AM.