I would be scared to death to put anything heavy in a heavy vise on top of such a small wheel. Afraid it would fall over (top heavy) and break something important like my foot. JMOðŸ›
I can stack heavy weights on that wheel. That would help. I don't want to make it really heavy ALL THE TIME or it will be very difficult to move ALL OF THE TIME.
Plus, if the vise proves to be too heavy, I'll simply bolt my grinder on top instead.