I had a Mega SG and sold it for pretty much what I paid for it.
The money I did loose tho I chalk up to piece of mind and knowledge in knowing that I'm totally satisfied with an original Genesis plugged into HD Retrovision cables, into a retrotink, and into the HD TV we have in our TV room. I also can grab a CRT from the basement if I need to get that original fix.
This then led me to actually selling my early Retro AVS I bought when they first released.
I'm finding the retrotink2x to be the piece of equipment that allows me to continue to play my old consoles on HDTVs.