Hey Mike
I have never had issues with gluing flat sawn to flat sawn - - in fact, I think this would be the ideal grain orientation for the best glue up possible. Are you sure you were not warned against gluing end grain, cause that dog won't hunt? Many people have had problems gluing Ipe (myself included), but they have been due to the oils in the wood (or a bad batch of URAC), not its grain orientation.
In addition, if you are gluing bamboo to the board in question, you really do not have the situation you ask about, since the grain orientation in boo is not, IMHO, comparable to the grain in wood - and you can only use the boo one way. Just score the wood and boo (both sides of the joint) and glue away.
Although you did not ask - - I would vote for the boo ipe combo - makes a great bow and in my experience (couple of bows), the boo hickory combo results in too much set (probably due to a combo of moisture content, not enough hot boxing, and that hickory is much stronger in tension than compression) as compared to the ipe combo. Save the hickory for handle accents or backings. For that matter, if you have nice hickory, a hickory backed ipe bow is also real nice to have lying around the butts.
Russ
