Euro, the heater core issues have been experienced my myself and a few others to include laoutbacktrail. My problem is that mine doesn't get hot enough to produce heat once it dips below freezing. It seems to be gunked up, but flushing it only works for a week maybe two at most then it's back to being ineffective. Even after I flush though, it still doesn't make it as good as it should be, just better than it was.
I added an electric auxiliary heater on the passenger side center floorboard area as the passenger side vents do not seem to put out as much heat as the driver side. I don't mind the cold as much as I do the hot and humid. My AC works great and I'd rather have it than a heater that's optimal.
Just know that you're not alone in your heater issues. Just adapt and overcome, or since you've got access to it now, go ahead and replace it, but make sure you flush the cooling system very, very well or else you'll be chasing your tail again.
HTH