When comparing the 2 products or mixtures keep in mind that unless you know the date of manufacture of the Stain Magic along with the purity of your own Peroxide you may get confusing results.
Concentrated ( 35% ) Peroxide in its original container and stored in a cool dark place will in my experience keep it's strength for a year or more.
Dilute it down to 9 % in a used container ( even if you have rinsed it out several times ) and especially when stored in a moving and warm to hot van will not be any good after a week to ten days. So either mix in a new dark container and use distilled water only or mix small quantities and throw out whatever you don't use every week.
Stain Magic is a
superior product to the home made brew but only if it's fresh.
Do you know how long it was stored at the point of manufacture, how long it's been on the shelf at your suppliers ?
Fresh home brew is better than old
SM.
Fresh
SM is better than fresh home brew, imo