I just bought a Sonoma 13.5 a little over a month ago and I love this kayak!
I also have a SOT with nearly identical dimensions as your Dirigo and a faster hull shape. The Sonoma will be WAY faster.
It will also be way less stable. With a shallow V hull it doesn’t like to stay still when at rest. Initial stability is low, but secondary stability is excellent. You can really carve a turn in this kayak.
I replaced a 15’ rotomolded sea kayak (Necky Eliza) with this kayak. I don’t do longer than day trips so the single hatch compartment is more than enough. I’ve got oversized float bags up front that reach right to my foot pegs so it’s got relatively more bow floatation than the sea kayak did. It generally seems “faster” than the Eliza to me. Same width and the Sonoma is a much sharper more extreme Swede form than the Eliza with a slicker surface. I don’t have the strength to drive either kayak over 5MPH for more than a short distance and at 4MPH the Sonoma clearly takes less effort.
The Sonoma is also very light. It really makes a difference. I had trouble loading the 50 pound sea kayak, I have no trouble loading the 40 pound Sonoma.
The Sonoma feels like a sports car to me. It accelerates quickly, it turns sharply, it’s very sensitive to control inputs and very responsive.
The reason I keep comparing the Sonoma to the sea kayak is because the Sonoma is much more like the sea kayak than like the rec kayak.
These are the Harmony Gear “Long Stern Flotation Bag” They’re a bit over sized, but they have the super pointy skinny shape that fits into the very narrow space up there. If you’re taller you might find the “Long Bow” bag a better fit as it’s a bit shorter.