Dave is correct about the differences b/w SA timer and Web Mtns. I personnally have been very happy with the Web Mtn timer and find it very easy to set-up especially after doing it a few times, you get real fast at it.
The Hardware is the same but the software is a bit different in that the noise immunity is with the Web Mtn one only. Also from what I hear they are very close to a new switch with all the functionality of the SA units.
Nothing against anyone though I will say that the support you might need will be as important to Web Mtn as it is to you if that time comes. They are quick to respond and have plenty of knowledge on the intracacies of their product.