I am not sure how well the Canon and Nikon's 600 and 800 are selling...maybe real well but I am guessing the sale quantities are bitterly low.
But, where are the numbers high? The Super Zooms...Canon's, Nikon's, Olympus, Sony etc....that is the market that is selling at a relatively cheap price. I see a ton of birders walking around with a bino on one shoulder and a superzoom on the other. Now, those might be pretty inexperienced birders and ones willing to sacrifice a bit of quality for 'zoom' but those cameras are the ones selling.
Maybe the Tamron 150-600 is geared to winning back some of the super-zoom market by offering a price point which is competitive to super-zooms? The Canon and Nikon's 600 and 800 will not be touched by anyone other than people who make a living taking nature shots-----period. THAT is their market.
But the Tamron can make some inroads back into the regular birding world that the super-zooms have attempted to take. I would guess that the Tamron 150-600 would be much better than any super-zoom at distances between 10 meters+ ...
May make great inroads...
Amazing what can be done in PP. I have seen images that were in need of some serious help turned into stellar images. I think that ultimate image quality is getting less important than ones computer skills. I think I will use the money saved to take some crash courses in PP. So if I can become truly proficient in the PP game may be that I can get by with a lens that cost less than a car and be a happy camper..
to me, this is a great range in a reasonably priced package that may be a great performer in bright sunny conditions, wont do a lot for Friday night football.