Toe-Jamb00, What a hoot!!!
I don't call using stair material as being any different that using high quality flooring. I have and do use both equally. The amber boo is stiffer but I do not believe any better than natural. I also use both.
Vertical boo is homogenous. Next to foam and actionwood it is as consistant as core material can get.
Using any wood laminations. Elm, hickory. maple. ect can lead to fits in proper tillering compared to using any material that has a universal tension and compression gradient. I would reccomend all beginners to use actionboo or actionwood lams . I believe , especially with recurve limbs that you will immediately produce a much better bow and you will learn faster with less effort and ruined product.
God bless you all, Steve