I travel with two but only use one at a time. I started out with a Progressive Industries simple surge protector {as that is all it does - about $100}. A couple of years later I upgraded to their EMS system that provides much more protection (about $300}.
With the EMS system I am protected against voltage falling too low or going to high vs simple surge protection. I use EMS as my primary device but keep the old simple surge suppressor for use as a back up in the event my EMS grows legs. I also have loaned the surge suppressor to a number of folks who had nothing and they were glad to have it.
Can't think of reason to part with the surge protector, nice to have a back up.
:C