My old GI said no red, purple or blue. My new one just said no red. So I guess they all have different opinions.
I also think the Miralax/Gatorade one is the easiest to get down. The only one I don't throw up from either. I also had to drink a bottle of magnesium citrate the next morning as well. That was nasty but a small dose at least and didn't make me go much.
Last time I actually only was in the bathroom for about 2 hours on and off and I was all done. It was the easiest prep I had ever done. I always start the clear liquid diet 1 1/2 days before the test though so that helps make the prep easier.
Oh and yes the Gatorade is used specifically to help you replenish electrolytes that you lose from running to the bathroom from the prep. It actually said that in my paperwork last time.