I know that people do back ipe with hickory and claim some success, my experience of these 2 woods is that hickory doesnt have the elastic strength to comress ipe. The bow may work and the hickory will appear to stretch but the fibres of hickory will be compromised. Ipe is a hard- hard wood, bamboo would get much more out of the ipe than hickory if you want a fast bow over an alright bow, Check this out with others though, dont just take my word , Hope this helps