Tamron 28-300 and which 105 Micro 2.8?

[Daniele Colombo]

Two info requests.
I recently saw in Outdoor Photographer a short ad concerning the new Tamron 
28-300: any direct experiences?
I'm going to buy a 105 micro f 2.8 for macro photos and portrait: anyone 
has personal experience with the new Sigma EX vs Nikon? In other words, is 
the quality difference worth the price difference?
Thanks for any suggestions.

Daniele Colombo - Italy