If you can windfoil with a 5m then a similar sized person can wing with 5m, actually I'd put the winger ahead for bottom end capability especially if it's gusty.
Even at my very newbie level I can wing through lulls I can't possibly windfoil through on the same sized gear (race gear is a different planet). Might take 2-3kts more to get started with the wing but once I'm up it's going.
At my local at least 4 wingers can tack on foil which is a total game changer in light wind, those same ones can pump through a gybe in a lull that'll have me slogging with a sail.
If your locals can't do that then what you've got are not very good wingers, it's not the gear.
I can fly the 5m wing in 8 knots, 5m windfoil in 10-12. For winging that is with a floating board and big 1800 wing. Currently I only have a sinking wingboard (sink until just over the knees on my 75L), so I need wind to get it to float. I also dont ride larger than 1480cm2 anymore because those foils get gradually harder to tack and the forces when landing jumps get brutal (prone to breaking). These gear choices makes my usable windrange rise to at least 12 knot gusts.
This is very interesting discussion and a lot of good points. IMHO
1. Foiling is Fun regardless of the discipline they are more alike than different. That said I think if you know how to windsurf your first flights will be easier on a WindFoil. However because Wingers do not have to switch their feet transitions are easier to learn on a Wing. Even if you don't know how to windsurf the same holds true but instead of 30 min to get a 100ft flight it takes several sessions on a Windfoil. My experience is based on both using big boards without footsteps and big foils.
2. From what I see in Maui, were there are hundreds of wingers and a few old windfoilers. The maneuvers and tricks the expert (not even pro) winger can do is more like the expert windsurfers. Carving up waves (in different ways) big aerials (if you want to jump real high get a kite). But the ability to transfer the power from the sail directly to the board does allow the windfoilers to do things differently. We have had discussions on the beach and it has been pointed out to me that Wingers generally depower in transitions while I like to use the power of the sail to turn up the G's in a carve. Neither is better, just different kinds of fun. So it depends what you like.
3. When it comes to gear, and ease of getting on/off the water all the exwindsurfers rave over how much faster it is and how much less is involved. The expert/pro level wingers are riding boards 30L or less and 1.4m wings on swells. However there is another side to this; these wingers rarely go past the break, that's ok because all they want to do is ride the reef swell or jump. While guys like EZZY on his custom 85L board w/ SAB 799 and a 2.8m sail will be a kilometre off shore ripping up a 10ft wind swell with little worry of getting back. And there have been times when I am able to get going quicker with the bigger board or drift in while my friends are swimming. Again it depends were you are and what you like.
So I suggest if you are thinking of trying windfoiling as a winger. Think about what you might like and where you are doing it.
Look, if you wanna hold an umbrella over your head while standing on a flattened tic tac, by all means go ahead. I prefer to fly past wingfoilers upwind in 9 knots doing 18+ knots pointing the eye out of the wind coz i love racing and i'm not interested in winging. In short, to each thier own. 
I started wind foiling early, about 6 years ago. Prior to that, my focus was windsurf racing. I got to the point where I could go out and get on foil and stay on foil for 90 minutes or so, until I ran out of energy. I haven't done much else, duck jibes or 360s etc.
I start winging about 7 months ago. At first, pretty disappointed in my level and progression, but invested in good equipment, Armstrong and f one, and can now go out and stay on foil for the session.working on foiling tacks and switching feet.
at this point, I still have all my foiling and non foiling windsurfing gear, but just want to wing foil. I keep the gear, thinking I might want to go back, but so far, I don't. I can pump my windfoil onto the foil as efficiently as most anyone, but I can pump onto the wing in less wind, using the 7 meter f one and a large , 1850 wing.
Equipment will continue to evolve, but racing will probably be more efficient, faster on wind foil, and with Olympic support, will hopefully attractive enough to lure some young people away from the internet. But, wing foiling will be the foiling sport of choice for wind sports, probably is already.
I still love windfoiling but started winging a while ago. Swell riding on wing is great and easy, wing foil takes a bit more focus. On an interior lake windfoiling to me is more interesting at it is more challenging.
The ease of learning winging over windsurf=>windfoil is a big point. Looking at typical summer locations a bunch of newbies takes a course, come back happy winging after 3-5 days and enter the shop to get some own stuff. To my observation the happy faces in windfurf schools show up a lot later and also less frequent.
To me it is basically a question of numbers/cost. As a total beginner you need to invest a lot less(speaking mostly new material) between 2-3k for a board, foil and 2wings. Seeing the latest price ideas for windsurf equipment nobody will want to start that. New Boards about 3k, sail 1k (you need at least 2), mast & boom another 1k.
