If you check the F4 Customs site, there is a price differential of about $70 more to buy a shield with a vent of the same size. There is also a small differential depending on whether you want tinted or clear. One thing to consider, if you ride a F3T or L is that the F4 screen has a fairly large gap at the bottom, so that, with the way it mounts, you already have a big vent. IMHO, an additional vent in the screen as well is rather redundant, but could provide some air circulation if you ride in very hot weather.
I ryde a 2017 F3L, and I'm now on my third different shield, with about 7,000 miles on my Spyder, and probably 1/3 that distance with each shield. I began with the short stock shield with the flip. The wind buffeting didn't really bug me all that much, as riding without any shield whatsoever has been my usual experience, in past. Out of deference to my missus' comfort (and some of my own), I tried a 23" tinted F4 screen. That switch provided a much quieter ryde with good handling and very little wind buffeting. We both enjoyed the comfort it provided. I concluded that I would be happier with a 21" screen, mostly because I prefer to look over rather than through, but that's personal preference. Also if choosing again, probably would just go with clear instead of tinted; personal preference after testing. I changed from the short stock screen to the F4 to gain comfort; however, having done so, I could no longer properly use my expensive BRP trailering cover - the extension 'pocket' for a taller windshield simply isn't wide enough to accommodate the F4 screen. That's something you need to consider if you have a favorite cover and are thinking of changing screens.
I later swapped out the F4 screen for a BRP 'tall boy' made for the F3L. My BRP cover now fits, but the ryde is windy and noisy, maybe even more so than with the short stock screen. I get a lot of whistling in my modular helmet. I may even just go back to the short screen again. The 'tall boy' screen is quite a bit shorter than even a 21" F4 screen would probably be. It pushes most of the air above my head, and almost above my passenger's head. Some, but not all, of the wind buffeting is reduced; however, on-coming semi's on a two-lane highway can still give a noticeable, momentary 'blow' as they go by. My sense is that the F4 screen deflected this more, while the 'tall boy' allows more to hit my chest. However, none has really affected operation or control of my bike.
Your experience may differ; your sensations/preferences may not be the same. I'm 5'10", have a stocky build. I'm still searching for the most comfortable result. Likely will continue to seek out the 'perfect' screen, then alter my cover to fit. The above is offered in hopes it may help you in your quest.
Cheers.
Cheers.
