Other answers have already said what I'd have said, apart from the fact that the only reason I'd use one of these adapters is if I had Canon lenses and you want IS. Having IS is arguably the most useful advantage these adapters offer, as shooting with adapted lenses with dumb adapters is quite simple.
I'm looking to use my husbands EF 24-70 f2.8 II and EF 70-200 f2.8 USM IS II on the Sony a6000.
I'm sure you must know this, but for general information, note that the size and weight of these lenses is significant and, if you do this, mount the lenses on a tripod or monopod and do not rely on the Sony's mount being strong enough to support these lenses.
Using these lenses on a DSLR is less of a problem for handling and balance, but on a small camera like the A6000 it just feels weird in my experience. YMMV.