I could write all day on the subject of K1s.... but don't worry, won't bore you!
First up, many guys get into surfski to paddle skis, and in the type of awesome locations we can only access on skis. So for many, getting into a K1 is never on the cards.
However, I do believe that paddling a K1 has a very positive influence on surfski paddling, both from a technique perspective and work output. As Jamie says, there is no hiding in the K1, so if you're going to paddle hard, you're going to get a great workout. One of the main things I see in guys who come doing demo paddles, or join my training group, is locked up hips. They appear to be getting leg drive and rotating their upper body, but their hips are locked on the seat. This has many negative effects on performance, stability, technique and often injury. Seized glutes are the order of the day. Fortunately it's very hard to get a K1 to run if you don't get the hips moving on the seat, so your technique is improved, as well as the timing of the stroke.
I've actually just finished a blog on this subject which I'll be posting on
www.thinkkayak.com.au later this week. Just need to add some video to complete it.