We didn't do GAPS but did dabble with Specific Carbohydrate Diet (similar). There is a pretty steep learning curve, but once you get going - and remember to make large portions so you have leftovers! - it does get easier. We also did the Body Ecology Diet for a while - 2 months off all dairy and most grains (except for millet, and also quinoa & buckwheat which aren't true grains).
A lot of Paleo meals are GAPS-compliant too, since it's primarily meat/fish/poultry/eggs, fruit/veg, and soaked/sprouted nuts & seeds, no grains or dairy, depending on whether you tweak it (some Paleo folks do some dairy - we do yogurt only). Pretty easy to avoid allergens when you're cooking from scratch.