Anybody reading this, do yourself a favor: do not think the OSR is all about clones. That's what I did. I convinced myself that the only way to get in touch with my gaming roots was with a clone. The clones are awesome and they do an awesome service to our hobby. They get a lot of positive ink in reviews for their "restatement and clarification" of the old rules. That praise is well-earned, because they do collect, codify, and clarify many things that may have been spread across multiple sources. But never make the mistake of thinking that the clones ARE the OSR. They aren't. Technically, OSR stands for Old School Renaissance (or Rules, depending on whom you ask). For me, from now on, it stands for Original Source Rules.
If you can realize and accept that supplements, no matter how many "Official" labels there are attached to them, are just somebody's house rules, then you can really dig in and find your roots. It doesn't matter what your OSR of choice are, get back to the core, the kernel if you will, of them. Then, from there judge the absolute necessity of any additions or changes in a glaring light. If it meets your criteria, then install it, but do so on your terms. I'm all for the D&D at my table being my D&D, but it should always be D&D. Too many additions, changes, and house rules and it becomes a case of "I like a little D&D with my house rules" instead of the other way 'round.