Tipping over is a risk you take when inproperly operating a machine. If you use it wrong chances are something will go wrong. Know your machine and its capibilities and nothing should go wrong.
I have used the dingos both stand on and walk behind. I like the stand on cause you have a better view of whats going on.
I checked out the Ditch witch dealer today on a rental for one because I need to rent some sort of mini soon if I get the job. I was very impressed with the sk650, love the controls and the platform. I will deffinitly be talking more to the dealer in both renting and eventually purchasing one. I briefly demoed the SK650 as well. For 20k I know its a big investment but if I play my cards right it will be a big return.
The vermeer dealer treated me like crap as the asked how old I was I said 18(turn 18 about a week) I did step on one but wasnt very impressed. There out of the picture right now.