I have read a lot of posts where ladies say they prefer to have the professional relaxers applied by a professional, but feel comfortable doing the store bought relaxers on their own. Is there a major difference between the two? Are the pro relaxers stronger or harder to apply? Do you notice a difference in the way your hair turns out if you use a store brand as opposed to pro? I'm wondering because I'm still deciding whether to do my own retouch in February. TIA