Buying a K1 to improve ski paddling stability???

Yesterday I picked up an old Cleaver "Max" K1 built for river racing, full kevlar and trailing rudder.

I bought it mainly for some river based adventure races but after paddling it I thought this will really improve my core stability on the ski.

If I was to rate it as a ski I would say there was no primary stability but secondary stability akin to a V10/Mako 6.

This lack of primary stability is what makes me think that trying to get out in it at least once a week will really help the core stabilizers to "switch on" much better.

Anyone else like me not coming from a kayaking background discovered any advantage of cross training in these unstable boats

Yes Ive been paddling K1's and Skis over the past 1-2 years and there is no doubt that K1s add to core stability development. It also makes for a change so that you're not always paddling the same boat. K1s get addictive on flat water and you may find that once you master an intermediate boat like the Cleaver Max, you will be looking for another upgrade, and once you do you may find the cycle starts again. That was my experience anyway. The challenge of being able to paddle a super sleek K1 well is an enjoyable journey that could take many months if not years - I'm still trying and although I still have the odd swim, they are getting fewer!