You're making general statements (blanket) and seeking definitive answers., no offense. The rule of thumb is if your safe on pump with iron you can increase 1point to compensate for thermal efficiency of aluminum. Now if your safe on 9.6cr iron can you get to 10.6 aluminum? I'd say you would be happier with 10.25 and again this all static without factoring cam events. My personal belief is 9.5 iron no quench open chamber. and 10.25 aluminum closed chamber with squish (quench .045) static CR. And keep dynamic CR (more important) at 7.5-8:1 iron and 8.25+ (the plus can go to even 9 with exact tune) with aluminum on pump. The lower numbers leave a little meat on the bone so to speak if the temp rises/humidity drops you get a bad tank ect ect. You will get all kinds of advice and some will tell you to run 10.5 ect. The further you push the edge the less room there is for error. In all fairness most parts come in large. I.E. Piston volume is 6 and not 5, head gasket are .40 not .39, chambers are a cc or so large as cast ect That margin keep a lot of "10.5" engines safe. You'll never have hard answers till you pay someone for their time, expertise, and equipment to sort everything out with exacts.