Tamron lenses for concert photography?

[McCrackus]

I'm a semi-professional concert photographer looking to upgrade my lens inventory. In particular, I really want a 70-200mm 2.8. Canon's version is fantastic but really expensive. I noticed Tamron has one for about $800, which seems really hard to beat. My main concern is that I hear a lot of complaints about Tamron lens' AF slowness. Concert photography often does not allow much of a window of time to get your shot. My question is, are there any event or concert photographers who have experience using Tamron lenses? Are they great value lenses/is the AF issue blown out of proportion, or is it a crippling game-breaker? If you want to get specific, the Tamron lenses I'm eying are the 70-200 2.8 and either the SP 28-75mm F/2.8 or the SP 17-50mm F/2.8 VC.

EDIT: Just realized there is a similar post asking about the same lens, but I don't see any mentions of the AF, which is where my real concern is.

 

[MLeeK]

I answered your questions in the other post!

 

[McCrackus]

Yes you did, thank you!

 

[myvinyl333]

I used to use Tamron lens on my D300s but had focus issues in low light. I now use the Nikon 24x70 2.8 80% on a D800 and the 70x200 2.8 on the D300s. Nikon over Tamron.

 

[n.hubb22]

I used to use Tamron lens on my D300s but had focus issues in low light. I now use the Nikon 24x70 2.8 80% on a D800 and the 70x200 2.8 on the D300s. Nikon over Tamron.

thats a killer setup!!

 

[myvinyl333]

I used to use Tamron lens on my D300s but had focus issues in low light. I now use the Nikon 24x70 2.8 80% on a D800 and the 70x200 2.8 on the D300s. Nikon over Tamron.

thats a killer setup!!

I do not have a grip on the D800 so with the 24x70 it is very light and almost compact, to a degree. The 70x200 is a beast but worth it~