Traeger's customer service is actually really good when you can get it. Hopefully you don't need it. It just takes a lot of effort from the customer to get to someone that can actually help you. They don't seem to respond quickly to e-mails. And when they do, the responses seem very automated and generic. Best way to get someone is to call them, tell them what your problem is, and you want the outcome to be. Or else they'll just walk you through their script and have you troubleshoot for way too long before you get to the same conclusion.
I wouldn't hesitate on buying the Pro 575 or any other Traeger model. I would, however, try to confirm that the one I'm buying doesn't have the dreaded 02.00.00 firmware on it before I took it home with me.
The complaints I see on here the most are with the WiFire controller (buying one that doesn't have 02.00.00 will save you a lot of headaches) and the amount of expected smoke. If you like your smoked food to taste like an ashtray or like your eyes to burn from smoke when you open the cover, the Traeger isn't for you. You should expect a nice smoke ring and a mild but tasty smokey flavor. Overall, they are very easy to cook on but need to be cleaned more often than a propane grill.
Also have to consider that most people join forums to either ask questions or get help with a problem. So even though there are a lot of complaints on this forum, there are a ton of Traeger owners that never had to come on here to ask for help. Check out social media too. Seeing people talk positively about the brand might help you with your decision.