Chapter 21G … you say that HQ and NQ have the same spiritbond rate.

When did that change? IIRC each Materia adds 20%(?) to the points gained towards Spiritbinding, and HQ adds another 20%(?). I am not positive about the 20% number but I do remember that HQ bonded faster than NQ, as though HQ status was another Materia melded to the item.