Need advice on remote starter for 2002 Altima.

Hi all, I have a 2002 Nissan Altima 3.5 SE. Nissan tells me that if I buy a non Nissan remote start all sorts of bad things can happen. Of course the Nissan version costs a lot more than what I can get somewhere else. Previously I have had off brand starters (Viper) installed on my Pathfinder and my Mazda with no problems. What's the scoop on this? Is it just marketing or is there some validity to it? I am willing to pay but not if it's not necessary. Thanks for any info. Gary