I have the 2018 26" which is very stable for me as an intermediate 62 year old 76kg 5'10". With its giant concave and everything going on under water there is a lot of wetted surface area to overcome. It's certainly very stable for a 26 but all that surface area makes it rather sluggish for a 26 and hard to get on a plane by paddle alone.
I recon you would soon tire of dragging 28" thru the water and would soon have a lot more fun on the 26".
Its a great board for in and out of the surf. Good and strong and not a dugout. Downwind in close bumps you are either sticking the nose in or dragging the tail.
Hopefully some Port Phillip paddlers will chime in with their views. Not having to negotiate a surf break would suggest to me a lot of other boards that would much better suit your Bay.

I'd suggest demoing a Maliko 14x28 in the typical conditions you paddle in, if I were you.

Unless you are a pretty experienced DW paddler, 26" wide boards can be a little bit challenging downwind for many. The Maliko 14x28 is a very nice and stable board that handles well in cross-chop and is generally pleasant to paddle and pretty easy to downwind, and makes it FUN.

Some boards are effective downwinders in terms of speed (in the right hands, anyway) but they aren't much fun to paddle. If you aren't racing then I'd suggest getting a board that is FUN and EASY to downwind, not some twitchy technical race board.