The temp accuracy will be better on the Pro 575 / 780 since they use a more sophisticated controller. I also like to be able to check and change temp from the comfort of my favorite chair. That said, you will also want to get some accessories to go along with the grill so keep that in mind when working on your budget.
It is kinda a tough question to answer because you need to balance how much you're willing (and able) to spend vs. your expectations. For example, if you spend $500 to stay within budget and aren't happy but spend $700 and are very happy, then going a little over budget is probably a good thing in the long run (just made up numbers of course).
A few things to keep in mind when looking at a pellet grill in general, and Traeger in specific:
- Pellet grills aren't "smokers" in the sense that you'll get the same smoke flavor from say an off-set smoker. Many people who want more smoke use things like a smoke tube (very cheap on Amazon)
- Traeger temp probes are notoriously inaccurate so you will want to consider a good 3rd party temp probe. Many of us here use Fire Bird 2, Ink Bird or Thermaworks.
- Get a good quick read thermometer. You'll use this a LOT.
- Don't be afraid of "too much space". When I first got my Pro 780 I thought it was HUGE! Now I really appreciate the space and sometimes wish I had more. I find myself doing more and more sides and other items on the grill along with my main course, so the space is handy.
- While the insulation of the Iron Wood and Timberline is nice for cold weather, those grills are $$ and many of us here use welders blankets or other insulation for our cold weather cooks.
You can find good discussions on all of these points on this forum. Good luck!
It's amazing how quickly you can fill up space. And the WiFi connection makes life so much easier as you can control the grill from anywhere you have an internet connection. That may seem like overkill, but the first time you do something that will take more than an hour, you'll appreciate being able to go out for the day and monitor your cooks. And as Murphy's Law said, you'll need lots of accessories as well, with the first purchases being an InkBird or Fireboard WIFI (not Bluetooth) set of probes and a smoke tube!
