Since Edge came after the 488s, sometimes called 500s, were dropped, I can only assume you mean the 550 engine. It is well known and documented that those engines tend to have problems. You might get 500 or you might get 5000 or even double those miles before they poop, but often they do. It is not an engine that can be counted on like it predecessor fan cousins. It is not an engine that has arrived in its final form - except perhaps in the last couple of years. Time will tell.
There are so many variations of the engine over the years they have built it. One can see it two ways; either you can appreciate the fact that Polaris has continued to refine what is a fan with nice power (for a fan) to try to make it a worthy engine, or you can wonder (as I do) why they took what seemed like some good steps in creating an improved engine, and then let the market do the test running for them. Personally, I prefer not to be test running a machine when I am alone in some remote part of Alaska, far from the nearest traveled trail or settlement. I could resurrect an old Mercury, Chapparal, or Evinrude snowmobile if that was what I wanted to do.
I have a 550 Edge Super Sport myself. It has about 7000 miles on it and has only been rebuilt 3 times. When I go out today, it will probably be on my old 488 trail. 21 some thousand miles and the untouched cylinders and new rings (w/ 8000 miles on them) still give me 100 psi or better. At least if she lets go, she'll do it with credit to spare. Not surprisingly, Polaris does not acknowledge that engine for its reliability.
I would add that, while the problem is obvious: the engines fail, the cause(s) is/are not so obvious. I think we would have seen them fixed almost right away if the cause had been easy to diagnose and correct. (That would be another good argument for doing the testing in-house; it's really hard to know exactly what happened when customers bring the product in after a failure.) And overheating itself is not often a cause, but rather, a sympton of another problem. I do think there is too much heat due to the size of the cylinders and not enough of a margin to safely get rid of that which is why the engines fail in some circumstances. I think that is why the last two years have the engine being built with the more efficiently cooling plated Nicasil cylinders instead of the long lasting, but less effective in cooling, iron sleeved cylinders. It's and undesirable, if neccessary, move, but it may work to solve the sometimes0heat problem.