Even if the pros testing/endorsing them wanted to wear them, I'm not sure they could without getting league approval first.
They're definitely not cheap, but they'd be more expensive to produce than most holders because there are more parts. They're also being produced by a smaller company in smaller numbers than the most popular holders; that also drives costs up.
You'd definitely be limited to the proprietary runners; it'd likely be a stainless steel runner. No one knows for sure how they'll hold up over time right now. It seems like they've been testing them for a while now.
It's not the same thing as profiled steel - it's allowing more blade to be in contact regardless of the profile. You could use a custom profile in conjunction with these holders. The same profile with these holders and traditional holders would allow for more steel contact in turns.
I don't think they'll necessarily get more traction from players learning the game. They'll get traction from people willing to spend money to possibly gain a competitive advantage and that could be players of all levels. With that said, it'll be a niche product to start for sure; I view it as similar to Sprung in the inline world. I think the Sprungs are better than the stock chassis on most skates, but most players are fine with the stock chassis and aren't willing to spend the money to buy a new chassis. Most people are also comfortable with the stock holder on their skates and aren't willing to spend the money to swap it, but there are those who do and will.
While I did spend the coin on the Sprung chassis for inline, I did that because I played ice first and was always searching for that ice like feel in inline (had already used the Tuuk Rocker chassis). For ice, I'd have to be shown that there would be a DRASTIC improvement with the new chassis to consider spending the money on the new chassis and getting it mounted. That's why I'm also in the wait and see camp on this, but the concept is interesting.
Oh, and for those wondering why I compared this to the Sprung holder in inline vs. the Marsblade inline chassis; I don't have the numbers, but think Marsblade may have sold more to ice players who don't even play inline on a regular basis because it was marketed as a training tool.