After following this thread for some time, I decided to buy Tamron 70-300mm VC lens as an upgrade for my canon 55-250mm IS lens.
I did compare both lens and VC on 70-300mm is way better than IS on 55-250mm.
Posting few pics taken with new lens, all Cropped and edited.

Western Scrub Jay

IMG_7365

IMG_7336
Nice shots!
I think this lens is an under rated lens. If focuses fast and the VC works very well.

...but having used a 200, 250, and 300mm, I personally didn't feel like I gained any practical advantage with the 50mm difference. Then again, I wasn't shooting wildlife. FWIW, the other member might not even be looking for extra reach, and regardless, he already made his purchase so our opinions don't make much difference to him.




