Replace Bags or Switch to Springs?

Well the inevitable happened to my wife last week. She calls me and says the
Self Level Susp Inac. is showing (something I see here almost weekly but never
had it happen) and the ride is bouncy. I immediately knew what happened.
I stood outside just to see what it looked like coming around the corner and
sure enough it looked like she had 92 dead bodies piled in the back. I restarted
it and the pump works, but a loud hiss is coming from the left rear, then the message pops again. They lasted over 170,000 miles so should I switch to springs now or
get new bags?
I really can't tell which is more cost effective at this point because from what I've searched the bags are the cheaper route, sprins last longer but who says new bags
will not last another 170 or will the X last another 170

Also, I saw the list for the conversion, but cant find out if I need a spring
compression tool.

just change the rear bags, Arnott bags will b good
change both

alot of DIY articles on bag replacement, ppl say its quick and ez