Heater Core Questions

[BrianG]

So, I'm considering just replacing the heater core on my truck during the rebuild. I don't really want to find out later that I should have done it now. One option, is to take my old one to a radiator shop and have it checked out. The other is to just order/buy a new one. If I decide on new, I've heard that many of the new ones are aluminum instead of whatever it is they are from factory (brass, bronz, copper????). I've read some negativity toward the aluminum heater cores... so... my question is why??? I probably will hardly drive it in the cold, so if its just a little less on the heat output then I guess I don't really care. Can anyone with experience in this matter please provide some insight into this.