Upload & Sell: Off
I just can't see why one would grab this over the (excellent) sigma, the nikon 2.8 vr1, or the new F/4 nikkor. You know the AF on the nikkor will be superb, and limiter is good... tamron and sigma have no limiter.
But why pay 250 more for the Tamron (unless maybe it is much better optically, guess we'll need to see comparisons). I trust that the Sigma can take some abuse though, Tamron kinda scares me after seeing that 24-70mm VC stuff with the element falling off it's glue point. Also you know the Sigma's rendering and bokeh are fantastic.
Plus, with the Sigma, you already know that it performs very very well with the Sigma 1.4x. The Nikkor f4, well, you can bank on it being rocking with the Nikkor 1.4x, hell, at f/8 I bet it's better than the 2.8 sigma with their 1.4x tc at f/8 (maybe not but wouldn't surprise me given how great the new Nikkors have been). How good will this thing be with the tamron 1.4x...unknown. Maybe great? I hope so.
Don't get me wrong I like Tamron, gf had their 70-300mm VC and it was very good. But I think this lens needs to REALLY prove itself reliability wise, AF wise, and optically.
I just think this lens shoulda been smack dab priced at $1249, with a temporary $100 mail in rebate like Tamron loves to do. That way it'd get some appeal over the Sigma.
The Canon side of things is probably even worse, because their 70-200mm F4L IS can be had even cheaper, and found for under a grand used any day on craigslist, and can be found as a refurb much of the time as well. I remember Sigma coming out with their 70-200mm OS and charging too much for it and then manning up and saying "yeah we screwed up" and dropping the price. My hunch is Tamron will correct the price with rebates. The saving grace would be if it is optically amazing, up there with 70-200L IS version 2.
The macro lens, we'll see. It's creeped up into near Nikkor and Canon territory. Sigma can get away with pricing the 105 and 150 (and new 180) lenses fairly high because they are arguably some of the finest auto focus macro lenses ever made and the 150 and 180 are almost a true APO design...The 105mm isn't, but still has much less long.CA than the Canon 100L. What you lose out on is that hybrid IS from the Canon side, and the L branding/resale value/confidence.
I guess the Tamron has weather sealing. Nonetheless, I was expecting about a $100 less price point for the 90mm VC.
They could get away with it for the 24-70mm VC. It offers something no one else does. And the Sigma product in that segment isn't in the pack of the new "wow, they really stepped up their game" products, it was released before that. The Nikkor is pricey but amazing and the new Canon is INSANELY pricey but amazing.