Sigma teleconverters have a protrusion so the mechanical compatibility is same as the Canon extender which is similar. There is a model of Tamron which does not have protrusion, I'm not sure what specific model it is though, and Tamron have made plenty of them!
The Sigma 150mm macro does NOT AF with a 2x from Sigma. This is a lens design choice made by Sigma. Presumably the Canon works in the same way with that lens. Both of those report their presence to the lens. A model of Tamron does not report itself to the lens, and therefore may still allow AF in that condition with unknown performance. Again I don't know what model it is.
In general, I would expect the Sigma 1.4x to work where the Canon 1.4x does.
Because you're trading the increased focal length, it does make the focal ratio of the system decrease accordingly. It isn't really a loss, but a shift in what goes where. These work essentially by magnifying the middle of the lens image. Good lenses may have sufficient quality that the resulting quality is still good. Bad lenses wont be helped.
Each model may arguably be better optimised to work with lenses from the same company. I've used the Sigma 1.4x and 2x with various Canon lenses, and in general it does what it is supposed to without significant impact. The only exception is the EF 135mm f/2L lens which really is horrible with a Sigma TC on it. But I think this is mainly due to the '135 being rather fast and also having relatively poor longitudinal CA in the first place.
_________________Canon DSLRs: 7D2, 7D1, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 10-18, 15-85
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 50/1.4A, 150 macro, 120-300 f/2.8 OS
Compacts: Sony HX9V, Fuji X100.