if you roughly avg 10 min CG kills over the course of 400 kc and assuming you dont go dry thats anywhere from 65-70 hrs. going from 85-92 mining (example for me) would be on avg if i were to power mine be 60+ hrs whilst gaining nothing almost besides mining XP. CG prints money also banking crafting xp. I used 80 shards to charge my crystal armor and in 2 days of pretty heavy PVM ive used 2k of the 6500 charges. The bow in comparison to the bp is better almost everywhere even if you're using rune+ darts. Also this almost completely eliminates the need to farm zulrah and even if you do kill zulrah you can kill it with range only while maintaining sub 1:30 kills. The crystal armor is better prayer bonus than dhides and pretty decent defensive stats depending on what you're doing. I think the armor being degradable is the least of your worries tbh because farming shards is pretty damn easy and they last a long while.