In general, getting one is a cheap form of insurance for a major purchase by you. There are some horror stories on the forum about mishaps which occured when one was not in place.
I went with the Progressive Industries EMS-PT50C, which is a portable model. Company offers lifetime warranty. Does more than just protect against surges - low voltage, reverse polarity, etc.
Good luck with your search!
Wayne and Kim
2014 Cedar Creek 36CKTS
2011 Ford F250 King Ranch 4x2 Diesel, added springs
Nights camped: 2014 - 32; 2013 - 23