Pros: easy to install, good customer service
Cons: instructions (at the time, they may have improved) -haven't thought of any other cons (price maybe and shipping if ordered from UK or Germany)
(NOTE price to the left is British pounds, not dollars (don't know what the exchange was then), and there was a special promotion that brought it down to £135.68 and that also made shipping free!. Interestingly, the same unit purchased from Wells today would be I £135.68, not including shipping. Note: do not pay the VAT (value added tax - I think!) because you are not in Europe.) I bought the VSB-b automatic door opener, a hen size door, and the timer (optional, you can do it with a light sensor alone) in November 2008, from Well's Poultry in England.
I love it!!
The timer malfunctioned in January 2010 and I contacted the manufacturer in Germany.They were very helpful (although communicating was a little tricky) and they sent me a new circuit board (easy to switch out) and I have not had any problems with it since. I received it only 8 days after I contacted them - which really surprised me. They just asked me to send them the faulty one after I received the replacement.
At the time I got it there were no domestic units available yet, so I can't compare it, but the ones made in the US look good and are cheaper (I think... need to check).
You might be able to get the unit directly from the manufacturer or Wells for less... I did - but you'll have to check around. I think I got it from Wells because there was a promotion. That said, they were slow in sending it and customer service was slow to respond.
The German manufacturers website: https://axt-electronic.eu/us/