I backed off on the ES (3 Tbs to 3 cups of GF juice instead of the 4 Tbs in the recipe) and it works fine for my wife and I. We didn't start "running" until 8:30 or 9:00AM Saturday. But we did coninue with the periodic runs untill much later that afternoon and even had one more episode (with stones yet) on Sunday morning. And neither of us had much in the way of nausea the whole way through.
The Clark recipe allows for substituting grapefruit or any tart apple juice (like granny smith) for water. Just make sure you get fresh organic juice or squeeze your own. Now that we have a citrus juicer (Black and Decker I think) we'll continue to by fresh grapefruit and make the juice ourselves.
Don't much about the every 15 mins mix. The Clark Flush works well and I'll be sticking with that one and make adjustments to it as we go.
Remember, most of this stuff is not engraved in stone so you can adapt recipes to you instead the other way around, as long as you keep the basic guidelines in mind as you make any changes.