Wood heater

Been heating my house with a fireplace wood burning insert for the last 15 years. I bought the unit used so really don't know how old it is. So I have had three contractors look at my unit and all three told me it was junk and I needed to replace it. I have to decide now with a new heater, Catalytic or non-Catalytic. Has anybody come across this Catalytic thing or know anything about it?? I find it all depends on the salesman as to what I should get because one will say yes and the next one will say no. Its very confusing for someone like me not knowing the different. I have a feeling the salesman just wants to sell me what they want to get ret of and could care less about what would work best for me.