To just introduce a brief comment, we know that there isn't really a "best" way to balance an arm. If we did, every robot in 2011 would have used that mechanism or whatever applied on their robot somewhere that year
Not know a whole lot of information on the best use of either, I really can't give too much help on this but I can elaborate a bit on both of them and one or two other things to aid in balancing arms or systems.
With surgical tubing, gas springs, and constant force springs (very applicable for elevators), they are ultimately going to have some constant force pulling/pushing the arm up or down (however you orient them). In this case, I wouldn't see a non-backdriveable motor an option unless you have an equalizing force colinear with that one being applied to your arm by your mechanism. (Someone please correct me if I'm wrong
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I know that some teams had great success in 2011 with just gearing right and using control loops to establish a great balance of weight without too much load.
To end, I do believe it does depend on how you are designing your arm and system and then from there a determination, from design to actual performance, you can asses your situation to move to springs, surgical tubing, ect.