Yesterday evening I borrowed Henks's Cetus as a preparation for a tour at sea on Saturday: just to get a bit used to her.
I paddled out of the harbour to the Alkmaardermeer and in the protected waters of the harbour the Cetus felt very manoeuvrable; the bow even yawning a bit at every paddlestroke. Dropping the skeg partially compensated for this.
Strange enough I did not recognise this the first time a paddled the Cetus for 15 minutes because I than concluded that the Cetus was only manoeuvrable when edged. That's how it is with testing: sometimes you have to change opinion though.
Once on the lake I felt quite at home in the Cetus. There was not much wind anymore but there will still waves from the stronger wind earlier this evening.
With the wind from aside the Cetus started weathercocking already at the 2Bft-wind. It could easily be corrected with paddlestrokes or the variable skeg; what you like best. I think that I can understand the weathercocking as the aft ship is quite wide and is, because of this, more shallow than average when compared to the bow. As a result the wind can blow the aftship easier away; which is called weathercocking. Contradictionary is the kind of integral skeg integrated in the stern: you could expect that this could prevent for weathercocking a bit.
This was the first occasion I could use the new skeg system with the locking ratchet. At first I fumbled a bit around to adjust quickly, but I think it is just something to get used to. If its easy to do in winter with cold fingers I don't know. But we'll see.
I paddled several courses in the waves and experienced the Cetus being comfortable and stable under the conditions as they were. I cannot imagine any, more or less advanced, seakayaker having stability problems in this kayak..
After an hour or so I turned back for going home, now paddling with wind and waves coming from behind. Under those conditions the Cetus was not very directive-stable and wandered to both sides. Dropping the skeg completely helped a bit but attention in keeping course was still required.
Being back I concluded that I could take this kayak safely with me at sea because the contact with seat, knees and feet was perfect. Finally a kayak that fits me without having to customise the cockpit. 
:In fact quite amazing as this is a high volume seakayak and I am not too big myself.