Yeah, the Bosch systems top out around 500-550W which is not enough to cruise at 28mph. Although some of their systems are designed to top out at 20mph assisted so they’ll likely spin out long before you reach 28mph. I just upgraded my Cross Current to 1000W and even that isn’t quite enough to cruise at 28mph all the time (although it’s way better than the former 650-700W peak power.) I think 1200-1300W is what up I would need to realistically cruise at 28mph in most conditions. Most people don’t realize that the power drops with decreasing battery voltage. So a 10V drop in voltage @ 20 amps would be a 200W drop in power although, in my experience, the real world drop is even more pronounced than this.

I think that my next e-bike will be a mid-drive system but most of them are still underpowered for true speed pedelec applications.