I also recently started to use Fences, and would recommend it. However, the persistence of Impulse with the latest version is enough to make me de-install the whole lot.
As an interim measure, I have used Zone Alarm to block Impulse at the firewall, and I have set DC's Process Tamer to force kill the two Impulse applications that run. The Impulse system remains on the hard drive.
It's not an elegant approach, I realise, but it does save me the time and effort necessary to find out what happens to Fences if I try and expunge Impulse from the hard drive.