Keep in mind a standup type for any given capacity will weigh more than a physically larger sit down forklift.... standup needs more counterweight due to shorter wheel base. Standups are tricky to brake going down an incline...foot brake, sort of all or nothing braking on the one's I've used. On the plus side they are handy when getting on and off the truck a lot to check the skates or whatever.
We don't have operator's licenses here, but your supervisor or someone from the forklift company is supposed to do training/certification. For a sole proprietor working in their own shop, there's no requirement for anything, but a smart person learns basic safety rules, and gets a minimum of training regardless.
Maybe the never ones are different, but if you have any ramps to go up and down forget a stand up. The ones I've been on the brakes are all or nothing via the dead man platform. You go down a ramp and it just takes off, then you have to step off the dead man platform and the brakes lock up.
I actually turned one over one time unloading it off a Landoll trailer. It was loaded from a dock which wasn't a issue, but where I was delivering didn't have a dock so I had to tilt the bed. I got on it to unload, stepped on the dead man platform and it took off. Well my first reaction was to step off the dead man, but that just caused it to go into a slide. It wound up getting sideways and when it hit the sudden stop and the end of the trailer it turned over. Threw me off of it in the process, and to this day I don't know how I escaped without the overhead guard hitting me when it flipped and threw me off. One of the closest calls I've had to dying.