I also had great upgrade percentage as a silver (30/32) over the first 9 months of the year. (in fact my upgrade percentage is actually worse now as a gold soon to be platinum). However there the benefits of gold over silver are extensive:

Always Sky Priority even if not upgraded. Zone 1 boarding at the least. 100% bonus miles (instead of 25% as a Silver).
Also rumor has it that that starting next year Gold medallions will be Sky Team Elite Plus which means lounge access on international flights regardless of ticket class.