This is a little off-topic, but I never considered having to hit the lock button on the MP3s to be a design defect. If you've ever ridden one, it is a distinctly unsettling feeling to be on one of those with the suspension locked, and rolling forward at a super low rate of speed (for example, when sitting in traffic on an incline and just rolling up a car-length).
Yes, you have to be ever vigilant when coming to a stop, or when
at a stop so the bike doesn't fall over...just like any motorcycle really.
They are cool bikes...I just finally wanted something a little more lightweight, and with less moving parts (ie front suspension) that could sooner or later go wrong...though I never had any issues with mine.
They have very reliable, long lasting engines, so if you are interested in getting one, you might still check out a used one....both of mine were used.
Past bikes: 08' Genuine Buddy 125, '07 Yamaha Majesty 400, '07 Piaggio MP3 250, '08 Piaggio MP3 500, '08 Aprilia Scarabeo 500
Current bikes: Two '09 Genuine Buddy 125's