5Dmk111 & Tamron 24-70mm f2.8 Di VC USD SP
Ι use it all the time, the lens is better in my opinion than 24-70mk1 canon, although it zooms nikon style, ''backwards'' and in my opinion the distortions are also higher.
Other than that is a nice sharp lens that focuses accurately and the IS ( VC ) works unbelievably well!
for the price it is a good purchase.
ps: I was also hesitant in buying a non canon lens, but this one is actually a very good one.