Given Toyota were quite clear it was a no quibble refundable deposit, anyone who was even half interested in the car may as well have thrown an order in and take a couple of months to think it over. If it turns out you don't want it and there's super demand still, you could flip it pretty easily or if the demand was all just 'omg limited production' hype and the excitement has died off, just cancel.
Whilst the car would appear to be an improvement from the GT86, it surprises me that there is so much hype around it, considering the GT86 never really flew off the shelves. I have my suspicions that 'limited production' is a demand creator for a car that Toyota were only expecting to sell in relatively limited numbers here anyway.