For what it's worth, this has been my experience as well (with 2 different SpyderXs on 3 different NX projectors). The color results were very close to my own i1pro2, as well as my calibrator's Klein K10 (matched to his i1pro2).Yeah I have used a few SpyderX and compared them to the two i1 Pro 2 I have. They have always been quite close in my experience.
Can you get a bad SpyderX? Sure it's possible, but it's the exception in my experience, not the rule. The SpyderX are much better than the Spyder5.
I would run both Gamma and Color with the SpyderX, and then toggle your iris manually between the cut-off points to see the before/after color calibration results in various scenes and decide if you like what it's doing.
If you don't, then revert the calibration and stick with gamma only.
Of course you can add an i1 Pro to your tools if you want to go deeper.