Like any accessories the looks are a personal preference thing.. I like the look.
It's hard to qualify how much they alter the airflow unless I do a back to back which I haven't done yet but may do one day soon.
One interesting observation while enjoying a ride in the rain the other day. The forward face of the winglets collect a lot of mist/spray, and as I was riding I could see the collected water (and direct rain) leaving a witness trail along the front face and dispersing as you would imagine seeing smoke in a wind test tunnel. It was very cool (almost hypnotizing) to watch, and confirmed the aerodynamic value of the part.
On the topic of warm weather riding with the winglets installed. I dunno,, but I can say that we have had a little more than warm weather lately, as in farken hot.. I normally try to avoid riding when it's much over 35c but we have been doing a lot of remote product testing and development that requires I have the bike on hand so hot riding has been the norm lately.
I can honestly say that I dont believe it would have been much more bareable without the winglets.
If they disappeared tomorrow, I would have a new set on order straight away, but like I said, that's just me.
Greg.