Bob: Any particular reason that either of these two Tamron lenses has not made it to your "lens List"?
Anyone: Do you have opinions about either of these two lenses?
I use the 18-250 on a canon 50D and I think I have good results from it. I am an amateur - I shoot a lot of grandchildren at sports as well as scenics. For the most part, I'm happy with it. I'm thinking of getting the 18-270 IS soon [for the Image Stabilization and for the extra "reach" at the telephoto end].
I had the 28-300 VC version and it was good for what it was. A fairly inexpensive 10X zoom. It took some really good pictures, and I cant fault it because I had the 40D on the green dot and was playing tourist with the wife and kids. And its $2000+ cheaper and about 3 pounds lighter than the Canon L version.