I bought a Cater Pro 3 years ago. I bought it during the off season and scored a pretty darn good deal. Here is my no B.S. Review.
1. I looked at multiple carts in use by different manufacturers to see what was out there. Are there better made carts? Absolutely. BUT and this is important! Ben's carts are not sold or advertised nor is it implied that they are the best cart out there. They are advertised as the best cart for the money. I would wager many people are buying them because of the lower prices.
2. I went to the Health Dept. prior to purchase. They looked at pictures, reviewed schematics and gave conditional approval. I knew what I needed to make them happy and pass inspection.
3. I secured my own financing. I did look into the what was offered on the website. This is a third party company, not the cart company. It offers a means to an end if you have no other options. After I read what they offered, costs etc. I chose not to go down that road. They were very upfront with the end cost.
4. I received my cart in the time frame promised. It was packaged very well, with no shipping damage when it arrived.
5. The cart was pretty much what I expected based on the price and looking at other carts.
A. Fit and fitment was so-so.
There were sharp corners: I sanded them down.
Not enough pop rivets in the panels for my liking: I installed more.
Steam table openings openings were too snug: Deadblow hammer and a block of wood fixed that.
You get the idea. If I bought a premium cart I would have been mad. You can't buy a tool for a Harbor
Freight price and expect Snap On quality,
6. All stainless steel body panels. They are from China. I haven't spent much time looking so I don't know if you can even buy US made anymore. If you have had anything to do with commercial HVAC, restaurant equipment etc., you know that15 years ago or more,stainless from China started being the predominate source used. Their stainless will rust. You can use stainless cleaners that will help coat the metal and slow it down but, it is the reality of source of origin. I chose to wrap my cart to avoid this issue.
7. Pans are aluminum from China. They are NSF certified. They will not rust. They will stain and hold stains from things that do rust. I have replaced them with stainless steel pans because that is my preference.
8. Sinks are stainless steel from China. They will rust if they are exposed to moisture. Chinese stainless rusts. If you choose the 4 sinks so you can wash dishes and have a hand wash station, you have not done your due diligence with your health department. They are too small for more than decoration.
9. Equipment is as I expected for the money. The grill is adequate but nothing beyond that. Given the nature of the business it needs to be replaced just for appearance seasonally. Griddle works great but it is a steel plate so it does need attention. Burners for the steam table are cast iron and put out an incredible amount of heat. But cast iron doesn't last forever.
10. My cooler is a Coleman 3 day cooler. It is not meant for anything other than keeping some drinks cold. Would a Yeti be better? I don't think so. You only operate a few hours at a time for the most part. Most health departments won't let you keep food in it, so why add 400 bucks to the build? I use it for storage myself.
11. Ben is the face of the operation. Keith runs the shop. Ben will readily admit that he knows Jack about the nuts and bolts of the back of the business. Ben is however a wealth of information about the business of vending to the public. That is his forte.
12. I have interacted with Keith on several occasions. Keith is an engineer. If you haven't dealt with engineers, you don't know what I mean. He is very smart and knows his stuff. He is also incredibly busy. He will respond to your issues. It just may take a bit. But, he is an engineer. He thinks and talks like one. He is not being rude when he answers your questions. It is likely something he has answered hundreds of times and isn't going to elaborate.
13. I have not dealt with customer service, so I can't comment on them.

Summary:
Are these the best carts on the market? No. I think they fit a price point. But, spending more will not mean you will not have issues.
Do they use parts from China? Yes. I would guess all of the cart makers do.
Will you need to tweak and fix a few things? Maybe not the first time you assemble it. But I guarantee you will if you use it often and especially if you tow it down the road. It is maintenance and the nature of the beast. Also do yourself a favor and research towing things with tiny tires down the road, it will save you some frustration.
These carts are a low cost (relative to a food truck) entry into mobile food service. If you do not perform your due diligence starting with the health department and working out from there, you are going to hit barriers. These carts are not a high end luxury piece of equipment. They meet a price point that may still seem expensive but are in line with other manufacturers at this market level. If you want premium, pay the premium price. These are meant to provide a starting point for people to work from. It is still a tool that needs taken care of. It will have issues. There is a learning curve to all of it. After 5 years in the food business I know that expectations (excitement) are not always in line with reality.