Have never ordered from Joe's myself, but I believe so. I think the website gives the nutritional info for each product so you can work it out for yourself on the Syns Calculator (on the SW website, if you're a member). I also think you can only bulk-buy too, which can be quite expensive and difficult if you don't have a great deal of room in your freezer!
The WW Premium Pork Sausages are half a Syn each, yes. If I want a meaty sausage, that's usually what I go for.
If you don't mind vegetarian sausages, Linda McCartney does a Rosemary & Red Onion sausage (don't knock it until you've tried it!) which are Syn free and absolutely delicious.