OK, here's my two cents on this. As a disclaimer, I've never had a remote start on any vehicle, and have lived in northern climates almost all my 51 years. Also, one of my pet peeves around here is how many people leave their motors idling while the car is parked (and the vehicles are usually, but not always, locked).
I think remote starters are bad ideas for 2 main reasons:
1. An idling car wastes fuel (zero miles per gallon), and this is a pretty extravagant and environmentally unfriendly way to have a warm car to get into.
2. Every auto manufacturer that I'm aware of recommends that a cold vehicle be driven (gently) to warm it up. Idling over 30 seconds or so isn't necessary and isn't recommended. Also, frequent or prolonged idling is generally considered "severe service" and is one factor requiring more frequent oil changes.
Block heaters can be used to warm the coolant and/or oil (but I never use mine unless the vehicle is parked outside and it's well below zero and I remember to plug it in). There's nothing like a garage, though. Heated seats are also pretty nice on a cold morning.
John R. Boyce
1983 280SL, Euro, 5 speed