RGB to VGA scan doubler converter / scaler?

Hi,

I would like to get the best possible image from the Jaguar onto my television, and S-Video from game systems or computers is not working properly with my current equipment.  Has anyone tried putting together an RGB to VGA setup?  I am wondering if something like this may be possible to adapt, since it is supposed to work with the Atari ST computers and the Jaguar Catbox has a compatible output.

http://www.ambery.com/rgbcgatovgac.html

It's not cheap, so I want to see if anyone has experience with this before I take the plunge.

Thanks!