Redgard works well when used properly. But, it is not a product where more is better! IT is only tested and approved when it is installed properly, and that includes thickness. TO do it properly, you really need a wet film gauge to verify you're getting the proper thickness. You can't check afterwards, because generally anyways, to do that, you'd have to poke a hole in it...not the best thing for a waterproofing membrane! Wet film gauges are cheap - anyone that uses a liquid applied membrane should have one. The biggest issue with liquid membranes is uneven coverage and pinhole leaks. A sheet membrane is more forgiving, and with the required overlap or seaming, there's some redundancy there (eg., on Kerdi, a 2" overlap on a seam is more forgiving than about 50mils of liquid membrane you may not spread out properly).