I dont have either but there are some amazing accuracy reports coming back from a lot of people who have the American (amazing for the price point). The American and the Guide are two different actions, with the American you'll have a detachable magazine (an issue for some).
The Guide Gun has an ugly stock in my opinion, I think it would look much nicer being one color instead of looking like a water colored rainbow. However I still want one as a large bore carbine, I'd use mine for a timber rifle (as if I need another). The stock spacers on my GSR (same as on the Guide) work well and the rubber pad is quite soft. The laminate stock of my GSR (again, similar to the Guide) has been in rain and snow as well as hot and cold and it hasn't been affected in any way that I can tell. It's been abused and still it hasn't warped.