What you are actually saying here is true for Test Cyp/Enth. Given 100 mg of Test C/E, 70 mg is actually test, with the rest being the actual weight of the Ester. So once the ester is stripped away, you are left with about 70 mg of T.
I'm not sure what the weight of the prop ester is, but it would probably be advisable to apply the same math and reasoning so you are left with about 70 mg of actual Test per week. This seems to be a "sweet spot" for bigger guys who lift weights.
I can't see the difference between 70 and 100 mg/week to be too extreme, from a side effects stand point.