If you design the bow correctly boo or hickory doesn't make much difference. For a beginner flattening a boo backing properly isn't what I would be recommending plus he has hickory. Use what you have absolutely nothing wrong with hickory backed osage - it is a superb combo. I also wouldn't recommend a beginner adding 3 inches of reflex. A straight limbed bow with low set will trump the reflex at glue-up bow with 3 that ends up having it reflex pulled out due to less than perfect tillering.
4th bow in you should be keeping it simple. Straight glue-ups. No perry reflex, fancy profiles etc. Make a straight limbed pyramid and tiller that thing perfectly. Trying to run before you can walk is the most common beginner bowyer mistake. Keeping the strain on the bow is your goal at this stage not such and such a design! A straight limbed pyramid will shoot as well if not better than most designs.
