How much do you think the Viper unit will cost? I mean its nice to have OEM all around but what improvements if any are there vs. factory remote start?
The Viper units (direct from Viper) range anywhere from a Basic remote start system @ $250 to a 2-way remote w/ a "visual" responder @ $540. You can check them out
here. Remember there are other retailers that sell Viper units as well – you don’t have to buy directly from the company – you might find deals, you might not. You’ll also have to factor in shop install fees if you won't be installing it yourself. Another side note is to look around for vendors on different forums you're part of as they may offer discounts on parts or labor for being a member of the forum... I was able to save a descent amount of money being part of a forum which a local shop sponsored.
As far as benefits for aftermarket vs. OEM... a remote start is a remote start; however, there are some differences. Range that the remote works varies between systems - something I would definitely suggest looking in to. Other than that, Viper offers an iPhone (not sure about Android) app that allows you to start (or lock, unlock, set alarm, locate in a parking lot, etc) your car from your phone from anywhere in the world. Although my remote worked within a mile range of my car, I noticed that the high tension wires and thickness of the cement in the building I work in affected how far away I could start my car; therefore, I opted to pay the $50/year for the iPhone subscription. I checked with my Mazda dealer and they were unaware of any Mazda App that you could use to start your car with your phone. Further, the phone app will prevent you from having to carry around multiple key fobs – you’d just need your factory Mazda key.
Viper also has a "convenience mode" which allows you to double click the remote start button from inside the car while it's running to activate the remote start brain. This allows you to exit the car with the keys in hand to run into a convenience store, back into your house quickly, etc if you want to keep the car running instead of turning it off, getting out of the car and starting it right back up again to keep it idling without the keys inside.
As for what robertk said regarding the engine shutting off after R/S if you open the door, that just sounds ridiculous – what’s the point of having a remote start then? Do you have the Advanced Keyless Entry system on your CX-5? Did they explain what the safety measure was? Either way, I’m sure an aftermarket R/S has a work around for this… if not right away, there will probably be enough people that complain that the aftermarket will create a work around.