Exactly: one thing is saying that it works, another is to state that, by doing a conversion, an average Joe like me can rely on a "bulletproof frame", like it should be better than a Varg with its newer design. That ICE frame has proven to be bulletproof for a different use.
Maybe some pros have liked some conversions, but they have probably liked those converted frames in a different way than if used for their intended purposes. And pros have liked the Varg, too.
I haven't seen pictures of this YE-01 without plastics nor of the Honda CR Electric, but they could have started from an ICE frame and then done some modifications that we don't see or notice.
Here are a couple of examples of what experienced people can do:
Some years ago I was a spectator of a race of the Supermoto World Championship and I noticed that a bike had an additional triple clamp, presumably to stiffen the fork.
On a magazine, I've read of a MXGP team who used steel cables run between the triple clamps to stiffen them.
I mean, probably such people would achieve something better than average Joe, converting a bike.
Can average Joe notice these differences? Well, some years ago a guy that became a friend of mine doing some supermoto trackdays with me invited me to use his 2000 CR 250 in a motocross track. My only experience in similar scenarios was using a supermoto in dirt sections of tracks and I had little of that experience. I was overtaken by everybody and I didn't even realize that the front tyre had gone flat. You may expect that, for such a noob, any frame would have felt right. Well, I found that 2000 CR 250 frame to be too stiff and when I went home I did some internet research and I found out that that frame was indeed notorious for being too stiff.
And just one last comment: from what I've seen, those conversions are so different from each other that the fact that some work well doesn't mean that if I do one myself it will be as successfull.