Potential replacement for 28-70/4

[Boris Liberman]

Hi!

I realize that this has been discussed to dust (if there is such a 
term)... So let's make it brief, shall we. :-)

How good/bad performs SMC FA 28-105/4-5.6 (not power zoom, but Tamron 
rebadged lens) compared to 28-70/4 AL. I do realize that it is going to 
be 35 mm longer. I am however interested in the rest of the differences.

Thanks.

Boris