One of the complaint I have always read about on the -10 was the VANS heater boxes. Some people complained that they leaked a lot, others complained that they were made of aluminum (too low of a melting point), others complained just to complain.
I will admit, that prior to getting my fuselage (and thus Vans heater boxes) I was not planning on upgrading the boxes. People will complain about anything and heater boxes are pretty simplistic mechanical devices, so I figured the Vans units were just fine.
Then my fuselage arrived and when I inventoried the boxes I had second thoughts. Again, these are pretty simple things, with that said, there is no reason to not have high quality parts here.
On the left is the stainless steel part that I order from Aircraft Spruce (Part # 08-06230) and on the right is the part that Vans ships with the fuselage kit. I may be wrong, but I think the aircraft spruce parts are just the Plane Innovations parts.
You will notice a couple of things. One, the Plane Innovations unit is stainless steel. It has nicely spot welded connections, the larger flat area on the flapper has some stiffening ribs pressed in (which I am sure help a lot with warping when heated), and finally the flapper and door have a 90 degree frame on them that look like they will do a much better job of closing out completely.
All in all I am happy with the Plane Innovation units. I will be installing them! As an added benefit, these things will take a bunch of heat in the unfortunate event of an engine fire. (Image from Plane Innovations).