Having accidently taken off without the canopy being latched in a Sportcruiser a number of times over the last 5years I can assure you that it is a complete non-event. You cannot fasten it back down in flight though. I usually just throttle back, fly a circuit and land. Not a problem at all.
Having built and owned a Sporctcruiser for 5years now I can testify that the Sportcruiser is an excellent aircraft and compared to other aircraft with a 600kg MAUW it is quite a rugged beast in comparison. Try looking around a Eurostar or Bristell for example and see how much sturdier the S/C is than the other types.
I would agree though that any aircraft of this type and weight is totally unsuitable for the training environment where customers/students don't give a hoot on how the aircraft is treated or abused. It is horses for courses really.
I personally certainly wouldn't want to go back to flying heavy, old, awful handling Cessna's or Pipers.