This is for my new IIgs system, trying to get it working with the Dell 2001FP monitor's VGA input, which might not even be possible due to the scan rate. NJRoadfan suggested it might work if I set the VGA adapter to the multisync setting. 

I have three different Mac to VGA adapters, and it turns out one of them is the Griffin MacPNP that you linked first. I tried the multisync settings using those instructions, but no love from the IIgs. I guess I'll stick with the composite video input for now. It works OK, even if the resolution isn't the greatest.