The K1 Reko will be more durable than the K3 versions, and will retain its resistance to turning for longer. However, I find it moulds up slightly taller than the K3. For that reason, I prefer cycling K3 Rekos.
The K1 Reko allows for great approach shots, and has enough give to be able to put some power behind it off the tee. It's got just enough stability to give it real versatility. It's also an *amazing* beginner's disc, having just the right balance of control, speed and glide to be able to cover almost anything. This would be the disc I'd hand an absolute beginner.
Great putter/ approach disc!