[Klaus]

We were simply discussing the target market for this lens.

Professionals would mostly go for the original brand - other than usually having a slight quality edge; these brands have a pro support network in the major economies at least. That's important if your money is at risk.

On the consumer-side, it's a battle between Tamron and Sigma. Just based on the paper-spec there's little to speak in favour of the Sigma as far as I can tell.

[Rover]

I've seen the local AP photographer use a grab bag of lenses on his dual Sony A1, including the Tamron 70-300 (E-mount). If AP bought this kind of gear for him, they must be pretty confident in that gear's abilities. :-)