I would suggest you also consider a La Marzocco GS/3. I run one of these on a cart with a flojet bottled water set up which is powered by a generator. I have yet to see the machine 'struggle' in terms of recovery (40-50 cups per hour) but the single group is definitely limiting when it's really busy.
For a grinder the mazzer mini will be way too slow for a cart. If mazzer is your thing you would need to step at to at least a super jolly or major. I use a Kony-e and super jolly e. They are both workhorses.
Sorry I have no idea about leasing options.
Hope that helps.