In the colonies of Australia, we're a bit behind. 20 years ago, it was all 28s, with the odd 30. I tried 30s in a 686 Onyx Sporting and it was a pig of a gun. Fast forward and I'm re-entering Sporting Clays. 30s are everywhere, and 32s are rare. Our Miroku Mk10s have ventilated barrels, and to me these in 32 are perfect! Even looked at importing a Mk38 Sporter 32" Teague from the UK market, but seems your Mk38s have solid not vented barrels. Ultimately, older I get, nicer longer barrels sight, and if svelte in weight, the long barrels can be a joy.
Cheers