Not recently, but back when our Playsight smart court was functioning I believe we had the data on some of our extended length racquet reviews comparing it to each playtester's racquet of choice, which was often a standard length 27" racquet. I also recall that the fastest serve I ever recorded on our Playsight court was with an extended length racquet, I believe it was a Pure Drive Tour Plus from 2018. That said, I also feel like the benefit is similar to what @McLovin
mentioned, sort of that consistency boost on first serves. Although it is only a half inch with most extended frames, it seems that I get more of my flat first serves in, so maybe it is a confidence thing, I feel a little taller on my serves haha. It also felt very natural and comfortable for me when I was mostly hitting two-handed backhands, a little more leverage and nice feeling for the two handed grip.