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first off, your earlier reference to those APS-H sensors being used professionally... Yeah, dude, I said larger than APS-C, cheers for perfectly illustrating my point despite framing it as a counter-blow *slow clap*
Yes, the EOS M is obviously an upgrade for the lunar stuff with the added bonus of being relatively super-portable for other applications.
I recommended the 70D to begin with if Sean wishes to stick with APS-C.
Yes, the 5D is absolutely an upgrade from the 500D, outside of the naff 20fps video offering. Do you not agree?
Lots of people are happy shooting sports with a 6D, though depends on one's particular demands. The last guy I met with one and ecstatic to be using it was shooting at the Men's Flat Track Roller Derby World Cup. Some people seem happier than others with it. One comment on CR from a 6D user claimed the IQ of the images made it preferable to the more AF-reliable 7D to him.
I was obviously highlighting cost with that footnote regarding the A7 and 5D... And I was referring to my own enthusiasm towards composing with the broader FF perspective, which isn't an option when your sensor's cropped.. If anything was, that wasn't intended as an attack on you personally - perhaps explains why it doesn't feel like I'm fighting with your shadow or whatever there?!
I've just bought a Pentax Q to test for pixel-density/reach and Micro Photography... I might yet revoke my EOS M recommendation in favour of one of these things