Just for an example, with the bike I know the best: Juiced Bikes ships their bikes -- most of them, anyway, AFAIK -- as Class 2. On my recent purchase, the sticker says class 2, so it's not just theoretical. However, a class 3 sticker was included, and the software is adjustable for class 3. So one might think that by using the included sticker, provided by the manufacturer, then setting the software for class 3 would be within legal guidelines. Juiced Bikes is famous -- notorious maybe -- for skating the legal limits, so I'm not convinced that this is accurate.
However, I'll start worrying about it when one of two things happens: (1) We get a rash of posts from people who were pulled over, the cop checked what class the bike was, and cited them accordingly for some infraction. Or (2) I myself get pulled, checked, and cited.
I just don't see it happening, unless ebikes become so common and there are major problems associated with them. No cop has so much as frowned in my direction over the last two and a half years of riding an ebike. I'll be surprised if I ever meet one who knows the difference between classes.
My plan is to ride responsibly and considerately, so I attract no attention from anyone -- pedestrians, other cyclists, drivers, police, or skaters. Hope it works!