I'm just a hobbiest. I have a 20+ year old CH 20 gallon compressor. Works, but loud. Looking at California Air compressors. The 10 gallon is rated at 5.3 SCFM @ 90psi. The 15 gallon is also rated the same at 90 psi, but lower at 40 psi (6.4 vs 7 SCFM). Does the gallon capacity just mean it will cycle more? Will they run air tools? Any other recommendations?