That's good to hear about the tension struts
I was going to do mine as well and was thinking of doing only the bushings but I have done that before on the E53 and was a total pita trying to change bushings while leaving the ball joint connected. I ordered the bushing and the arm in the end because I didn't want to be stuck if the bushing change didn't go well or the ball joint was worn out. It looks like the E70 ball joints are fairly large so good to hear that you have the 220k on them and still good!
I have only 110K on mine but I think I will do same as you and change the struts and re-bush the old original ones. This would be a good time to buy the specialized kit for doing the strut bushings on the car but the darn thing is too pricey for using only a time or two.