I’m not personally familiar with Refissa, but from the information on their website, it seems to be regular old Retin-A with an emolient for a moisturizer. There doesn’t seem to be anything special about the product. Regarding your questions, yes, it can be used with Obagi, and it is as effective as Retin-A because it is Retin-A. Micronized Retin-A has an advantage over regular Retin-A, but it appears that Refissa really has no significant advantage over any other Retin-A brand.