For a garment that has the felted join, I would assume that you would not be throwing it in the washing machine - cause then the entire thing will felt, not just the join...
If you're using machine washable wool - i.e 'superwash', a felted join will not hold, as it's not meant to felt.
A handwash garment will hold up just fine with both joins.
As for the Russian join, I haven't put anything with it in the washing machine. I would think if it's on gentle cycle it would be fine, as the join is pretty strong - when you're making the join, you're literally weaving the 2 ends into themselves.