More frw means you travel faster when you ww. This means less time spent within hitting range of opponents, but fewer hitchecks because you fly by faster.
You only spend less time in hitting range if you purposefully ww out of hitting range faster.
If its a barb vs caster duel just do shorter whirls to stay in range on them. In my experience faster ww speed is
always better. imho its just players that cant properly do short whirls that think its better to be frozen while whirling over someone. Just keep whirls short and stay within range, you hit the at the same rate regardless of how fast you are moving.
For ww vs ww, unless you are clipping someone (for which higher ww movement speed helps anyways), at all times that you are in whirl range and midwhirl, your opponent should be in whirl range for his attacks. I dont see how slower movement speed would help at all. You still do hit checks at the same rate, faster movement speed just gives you more control over the duel since you can leave your opponent's range faster if you need to.
Ive heard many barbs talk about how they have an advantage in ww vs ww when someone hf flashes them, but I dont see how that is true. The attack rate is the same regardless, you just exchange hits at a faster rate if you stay within range. Unless the barb is letting himself get clipped while you are hf frozen or something..