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Well if he does you will feel the difference in shifting even with lower end groupsets.
Tbh I take shimano's word as gospel; they generally don't 'recommend' more like tell you what to do to get the best result.
11 speed generation is the only instance where they specifically ask to use that and ship the shifters with it. I think the reason is the way cables exit the shifter. The short tongue cap has a locking mechanism so it doesen't rotate.
Yes it does ..