I must report that I am no longer a Tamron 150-600 user. I sold mine to recoup money to buy the Nikon 200-500mm F/5.6 lens.
Although I lost 100mm of long zoom range and 50mm of range at the short end, I gained a better 4.5 stop VR system, and an autofocus system that is faster and locks on better than with the Tamron. For an extra 320 dollars at retail pricing.
My finances don't allow me to keep both lenses. I would if I could afford to do so.
I made the tradeoff based on what's most important to my preferences. Since I like to photograph objects that are fast moving and often rather close to me, like at racetracks, the faster focus attributes and improved VR all pointed at the 200-500 as the more sensible choice for me.
If you're not pursuing racing photography, and are instead interested in wildlife photography, I think the Tamron is just fine and the extra 100 mm zoom range probably makes it your better choice.