I'm a little late since the OP already bought an esc but I like sharing my experiences so ..... The
max 6 will work fine on the factory motor but not much difference in power vs. The factory traxxas esc.
I wouldn't pair the
max 6 to their 1100kv in the xmaxx unless you like the smell of burnt esc. Ask me how I know
If you want to run anything other than the factory motor, Max 5 is a safe choice. It will easily push the 800kv and 1100kv HW cans as long as you gear correctly.
That being said, the castle XLX2 is far superior to the max5. Although complete overkill for an Xmaxx, temp is never an issue, regardless of gearing and ambient Temps. Castle's warranty is far better than hobbywings as well. Free replacement for a year and half price for 2 more years. Castle also offers trade ins. For $160 and your factory traxxas esc, working or not, you can get a brand new XLX2.
You can connect the XLX2 to your PC to make adjustments, or add the castle b.link and connect with your phone via Bluetooth to make adjustments on the fly which I find to be a very valuable feature. The castle software is far more detailed and the data logs are great if your into that sort of thing.
All of the above mentioned components I've personally used and abused. I'm currently running the XLX2 with the hobbywing 1100kv on a variety of mod 1.5 gearing and its flawless. I've never seen esc temp exceed 120, even on a 100 degree day.
I can't say enough good about Castle. Their headquarters is less than an hour drive from me so warranty is quick and easy. I've killed 3 XLX2s, all were my fault, and they warrantied them all at no cost. Great bunch of people.