Have had both 2020 wings for about two months now so I thought I'd share my thoughts. I Previously had the Naish XL and XXL so I was able to compare in some side to side before I sold those. Plenty of pictures online...so not bothering w/ any more foil porn. I'm a WWF style foiler (most of the time) and use a JP 7' SUP Foil Board.
First the Jet 2000. I was one of the lucky few to get the XXL when it came out in the Spring. As far as my eye can tell... it's the same foil, albeit the new 2020 Jet 2000 definitely feels lighter than the XXL. My guess is the XXL was the prototype. I loved the XXL and I love the Jet 2000. It's my GO-Too for down winding whether I'm WWF foiling or SUP foiling. It will slow down to a ridiculous speed when you need it too when connecting chop and has a great top-end for a foil this size. I will say that the new back wing 450 makes a huge difference in control and carving. With the old profile straight XL back wing, I would feel quite a bit of sliding and slipping when carving hard. Kind of like when you break your fins out on a surfboard. With the new 450 I've found that I can't get it to slide and thus I'm carving harder than ever.
The Jet 1650. The Jet 1650 is a complete redesign to the XL. And I like the improvements. The top end definitely has improved by a few knots. The foil is lighter. The low end is still there and this thing carves like crazy...for a 1650 size foil anyways. ;) Once again I think the new back wing is a big factor. At 6'2 180 lbs I can play with this in the waves till about thigh to waist, maybe stomach/rib high if it's a soft break.
Some other observations.
1) Occasionally the old foils would whistle...haven't heard a peep with the new foils.
2) Mast system so far has stayed very tight. BTW I'm using the Abracadabra system.
3) Fuselage is a little lighter due to the new geometry.
All in all...these two foils meet most of my WWF needs. I might get the smaller foil to surf some bigger waves but I'd probably rather be regular wave sailing at that point.
On another note, if you haven't tried WWF style wind foiling, you are missing out. There's something so liberating and just plain cool about going strapless, standing in a surfing stance and barely holding the mast for some forward momentum. Once you go straight down-wind, you usually just hold the mast with one hand. I'm actually disappointed with most of the major players this year. So many have the perfect shape SUP Foil board for this niche but they didn't put a mast track in as they are pushing the wind-wing. Why not both at the expense of 6 ounces?
Hope this helps anybody out there shopping.
Been thinking of a foilmount for my Fanatic Fly 9'6" sup.
Gonna mount it a foot behind fast slogging position.