I said the KB's were heavier than ANY other pistons I've checked, not specifically the Diamonds, that was just an easy comparison to make while I was at work and not able to look up a lot of sites.
I wasn't telling the OP what to do, just making an observation please don't take it out of context.
I can see where it wouldn't matter too much for a street/strip motor but since I race my car regularly, and plan to twist it 7200 and make about 650 HP or so I would think the lighter piston would be easier on the crank and rods. I'll pay the $200 - $300 extra for custom pistons and 60 grams less.