Upload & Sell: On
A) The 37-70 produces better color fidelity than any of the 3 Tamron 28-75 lenses I've owned or borrowed, All of the 28-75's I've used have had a yellow cast to them. Not extreme, but there.
B) The AF on the 35-70 is just as fast.
C) personally, I prefer the push/ pull over the Tamron zoom ring. It takes all of about 5 minutes to feel comfortable with it.
D) The 35-70 is built much better.
E) On FF, the 35-70 has better corners, no issues with decentering (I've seen that on 2 of the Tamrons)
I shoot roller skating pairs dancing for my daughter with the 35-70 and it focuses just fine.
As far as flare goes...loose the useless lens hood it comes with and get the metal HN23...Flare problems gone.