I don't know for sure, but it (intuitively) seems to me that you'd require a larger sample size because only 10% of the time will it explore other options. With A/B testing, you've got equal odds to hit either option, so each step is independent of the last; with this, each step depends on the previous results and thus if you have one option jump out into the lead (for whatever reason) it'd make it less likely that the other gets a good sample.