Hi *MC* and welcome to the WS School Forum.
The answer to your question is YES!
The Go and the Rio S handle very much the same when you keep the centerboard
on the Rio S in the up and stowed position.
So also yes, if you can stay upwind on the Rio S without the centerboard, you will be
able to do the same with the GO.
What keeps you out of the rear footstrap?
Perhaps not enough wind....?
The Rio S (at your weight) would plane at about the same windspeed I would think.
I'm not sure the GO is the "earlier planing" board that you are looking for.
Something like the Futura 155, with your 8.0 NCX would probably plane a bit earlier than
What you need for early planing is width, and a lighter weight board is usually better for
lighter weight sailors.
Put a larger fin (60 cm) in your Rio S and see if you don't get planing sooner.
You are not up to the full potential of the Rio S (what year model... 2008/2009/2010 or
the older style from previous years) until you have the footstraps all the way back and have both feet in the straps.
Hope this helps,