I went with them as well. Both shops were great and had good customer service. They found a minor dimple on my car bumper (I let it go since it is only seen under certain angle up close). And then recently I scratched my car door, they buffed it up and half the scratches went away.
My only my compliant is that at Kwun Tong shop, the road was so packed with trucks, it was a real pain getting my car in. The trucks won't budge an inch, even they see you are struggling and there are other trucks parked at the door or beside them.
The other coating services was more at half the price though. So I guess you get what you pay for here.