With so little really known about GT6 (as in only 25 people reported taking it for 24/25) it's really hard to take a view. If it ain't broke don't fix it but if it's coming to a question of stopping the riba or stopping treatment stop the riba and continue on the generic Harvoni.
Trials Data For Genotype 6
Sofosbuvir PegIFN-α Ribavirin
default: svr: 100%, trials: NEUTRINO 100% GT6 (6/6)
w24: svr: 100%, trials: ATOMIC 100% GT6 (5/5)
default: svr: 96%, trials: NCT01826981 96% GT6 (24/25)
default: svr: 97%, trials: No Trials - Based on GT1 extrapolation