I've been using (still am) that same unit since 2009.  It's protected my systems through many power outages and spikes/dips etc.  No issue's with it at all.  I did have to buy a replacement battery for it a couple times.  I also have slightly smaller units of the same type on other systems.  Also no issue's with any of them.
 
I have read comments over the years from some that say "you must buy only pure sinewave".  I have not found that to be a neccessity in my experience.

You're welcome...