Glasplies did have a reputation about the quality of their resins. They will now only supply reblended resins in you ask for that. They will supply 888x which is a 1st quality general purpose resin.
We only actually buy buckets, rollers, rep foam and hand cleaner from there. But i have never had a problem with them.
For the amount of money that you will save, its really not worth using reblended resins on anything more than flat roofs.
Steve