My thoughts:
- There are quite a number of different planes available. Most made by smaller companies. The question is what happens when a next economic low hits and the manufacturer goes bankrupt. Are you still able to maintain your plane? And what about certification?
- Most of that data seems about right. I do wonder if speeds of 250 - 300 km/h are achievable in a plane with a side by side configuration. The blackshape prime can do about 270 (150knots) with a 2 in line configuration.
- Most of these are in the MLA category with a maximum mass of 450 (or 472.5) kg. You are not allowed to fly these with the standard SEP PPL. Separate training, exam and licensing is required. And yes that is weird.
- The maximum mass of 450(or 472.5)kg is a big problem. Making a valid mass&balance calculation is almost impossible. I had a discussion with a police officer about this. Unofficialy he mentioned they skip the check on M&B for MLA aircraft because they know in advance it is overweight. And that would lead to a report, court case and criminal record. It might be worthwhile to check how they handle this in the locations you fly. (and don't forget any insurance implications)