The Sony TCs are designed specifically for Sony G lenses and CANNOT be used with other lenses without risk of damaging both the lens and the TC - this is due to the extremely tight tolerance (about a mm gap) between the lens' rear glass and the TC's front glass.
Likewise the new Sigma APO TCs are specifically tailored for a limited set of lenses such as the two Sigma 70-200 f/2.8 lenses. It is possible that they could work with the old or new Tamron 70-200 but I would take yours to a shop and examine them very closely, with the Tamron at each end of the zoom range, before shelling out. Tamron's own SP TCs (identical to Kenko's pro series TCs) get a wide variety of opinions, ranging from excellent to junk.
I use one of the Tamron 1.4x TCs on my Sony 100mm f/2.8 macro (making it a 140mm f/4) with fairly good results - rarely has to hunt for focus much more than the lens on its own. It does exacerbate the corner chromatic aberrations of the lens a bit, but shooting at f/8 (i.e. f/11 with the 1.4x) eliminates almost all of this.
Note that many older Tamron/Kenko 1.4x TCs and 2x TCs will not AF with digital cameras. If it has 8 contacts it should be fine. If it has 5 then steer clear.