30% does produce more power, but does not alter compression...only slightly affects timing. The SH .28 actually recommends it after break-in. In nearly any case, an engine will only need a shim or 2 added to bring timing back into the proper range. Larger engines (Big blocks .21+) are typically able to handle 30% without modification. The oil content is the same as 20% and the engine temps are nearly identical.

The only additional wear might be to the brass ring on the bottom and top of the connecting rod. This would be so minimal that over the average life span of 10-15 gallons, the difference would be negligible and would most like be completely un-noticed.