OK well in general smaller blocks have a lower orphan chanc…

OK well in general smaller blocks have a lower orphan chance. This is because other miners receive your block, process & validate it, & THEN switch to building on it if it looks good. Until they've decided somehow that it's definitely the consensus chaintip, such as validating it themselves & feeling sure it'll be built on, or actually seeing someone else build on it, they might just build on the previous block that they're sure of. As a miner you desperately want to get your blocks validated by other miners and built upon, so you need to make it as easy as possible. You could even be in a race with another miner who makes a block nearly the same time as you. Maybe you're a second earlier, but yours takes two seconds longer for other miners to validate, so you lose the rewards even though you got the hash first. That HURTS. Miners NEED those blocks.