True, with Prescription Blend you will be mixing 6 separate items. But they mix with just a few seconds of stir.
I don't know about your use of MegaCrop, but like most folks, I wound up with 5 ingredients: MegaCrop, Sweet Candy, Bud Explosion, Kelp Extract and 3rd-party cal-mag. And the stirring takes a couple of minutes for the MegaC to dissolve completely, and almost as long for the Sweet Candy and Bud Explosion to dissolve. (I'm still using version 1 of MegaC.)
I've been a big fan of MegaCrop and its Greenleaf add-ons. Ease and cost are huge benefits over my previous efforts with Advanced Nutrients and/or BioTabs. So far, with this test, Prescription Blend is looking real good. And I'd say that the prep-time for mixing a batch of each is pretty much equivalent.
Will be watching your test with keen interest.