I would say if you are running 8 tooth .325 vs 3/8 7 tooth , barely any power difference and would probably vary a bit due to soft or hard wood, hard to notice. Splitting hairs so to speak. 7 tooth. 325 will lower the chain speed but increase power. Biggest thing I notice with 50 to 60cc and 7t .325 pretty near every time I went that route was greater fuel consumption, more down time fueling the saw..325 is less grabby, so a bit smoother more noticeable in small rounds, branches and dead. My preference is 3/8 7 with a 20in bar, quicker sharpening, or a toss up with a 16inch bar 8t sprocket. 325 or 7t 3/8. If that is your biggest saw i would put the 20 on it, less back bending, very versatile. If a small saw fits your needs 16inch either 8t .325 , smoother, or 3/8 7t. is easy to sharpen and maintain, good if you dull your chain often such as flush cutting stump or cut dirty wood or just are bad at keeping the chain from the dirt.
