Bane works on RG’s it’s the reason why my N6M4 cold DH can explode Guardians, if it didn’t It would be a huge hit on dps (since I have 6 turrets that all benefit from the extra dmg).
My take is that running Long Arms of the Law to have 10s on Valor Critical is a better dps gain than bane since with Gogok of Swiftness I will have 23% AS increase and +15% CD reduction AND 50% more crit damage up for the entire fight with the guardian irrelevant if am in fire cycle or not, if I have to move to dodge out stuff or if there are adds or not. Having 100% uptime on Valor Critical - to me - along with 23% AS (8 more from Valor and 15% from gogok) seems like a much better deal than a flat 50-60% dmg increase from Trapped (which may not be up at all time if you need to kite / move away from some difficult RG and not be in 15 yards range and your follower doesn’t proc his slow etc).
Pretty much doing this (I dropped towering shield 20% BS dmg for the valor 10s duration) made it so I can clear GR 105 with 8-7m left after GR death depending on map / mob types instead of 2-3m left after GR death (when was running Towering shield, bane of trapped and bane of stricken or w/e is called that multiplies dmg vs GR / bosses each time you hit them).
I was able to reproduce this several runs in a row (the clear time) on various maps / RG’s so for me it’s better by miles than trapped. Am quite positive once I get some better rolls on my ancients and find an ancient Lantern to get last ancient in slot (and replace my shield) I can probably do 110 with 2-3 minutes left at my 1.2k paragon.