Neither manufacturer should really care much about the US market. They both sell 10x as much overseas as here. The rest of the world is way ahead of us in this realm and I doubt that is going to change much until the “soft” money stops flowing in to politicians pockets.
As far as the USA goes, it is the opposite of your scenario. Retrotec was not in the weatherization industry at all until a few years ago. TEC was 95% market share with Infiltec being the other 5%. From what I know it is approx 50/50 now a days and Infiltec fills in some voids. When a manufacturer has to discount to move its product line it may look like a good thing on the surface, but in reality there is probably a reason they have to do that to move product. There is a reason mechanics buy Snap On Tools, electricians buy Fluke meters, etc…despite the fact that way cheaper hand tools and meters are available.