Well with proper planning anyone can have a backup rangefinder available as the binos still function if the RF doesn’t, send in after season. But true it could happen at any time, doubt you take a spare stand alone RF in the field, crap does happen no matter if the setup is built in or stand alone.
Some complain about the weight of RF binos yet seem to not take into consideration the weight of their stand alone unit which they usually also have in a pouch on their chest rig.
No setup is 100%. I will say out of me and two other buddies using Leica and Swaro RF, none of us have had a complete failure. When I did get my first Geovid it did have the cold temp issue but in the replacement that never was an issue. I had more issues with my Sig and Vortex RF’s I used previous to the Geovid.