I own a GM-8. Used it extensively for many years. Edit: but only twice in the last 2 or so years.
I'm not sure if I would recommend one or not. I know the situation you are in, I was there when I bought mine (must be 7-8 years ago now). Back then there was no HEQ5 no EQ6 etc. My option was G-11 or GM-8 or Tak Temma or Vixen Polaris or the like.
I don't use it enough these days to comment with a fresh perspective. I also don't have experience with HEQ5 or such. But you may be interested in reading my review from all those years ago:
http://rogergroom.com/astronomy-reso...lescope-mount/
Regards,
Roger.