I had the K9 alarms a couple of years ago. Bought to replace aging Fox buzzers and being a bit of a techie these looked perfect. I used them for a few day sessions before taking them to France with me. The first evening I am sat with my mate in-between our pegs (about 10 meters from my bivvy) when my mate says he could hear a whirring noise - checked my receiver, nothing - glanced at my rods to see the reel on my right hand rod melting. Long story short, I had what felt like it could have been a PB, but because my receiver had not indicated anything it had ran at least 100 yards and eventually came off - I sold the alarms as soon as I got back and will never trust anything by ND again. The S9 alarms come with exactly the same receiver as the K9s.
I have Nash R3 now and have never looked back.