There are indeed differences between cheaper grills and a high end brand such as Lynx or Firemagic. We have a Lynx and aside from a faulty igniter, it has been great. Higher end models generally will buy you much better construction and materials and more features like better and more stainless steel, infrared burners, built in lights, smoker trays etc. It is of course up to you whether such things are worth it to you.

Keep in mind when shopping that not all stainless steel is the same. Basically, if a magnet sticks to it, it will likely rust at least superfically on you if you keep it outside. Most cheaper stainless steel grills are made of a 410 stainless or similar which lacks the nickel in other stainless such as 304 which is usually used in more expensive grills and offers better rust resistance. If you keep your grill outdoors, make sure you by one which is 100% stainless, because the rust will definitely find its way to the steel parts and rust out prematurely. Really it's all relative anyway; given the right environment any stainless steel can rust. The grills you listed don't mention what type stainless they use for the outer construction but it is probably 410.

If you want it to last it's also better to have a cast burner made of brass or stainless (304) rather than a stamped burner.

As I've said we have a Lynx grill which has an infrared burner for rotisserie cooking. We don't do rotisserie cooking too much but I can say it cooks very evenly and quickly and would defintely recommend it. Even the motor housing and skewer are by the way 304 stainless.

So really it boils down to how much you are willing to spend and how long you want it to last. Despite what others have said, there are real differences between the $1K+ models and cheaper ones, but they definitely aren't for everyone.

Stu