I've found proponents on both sides
Really? This is news to me. I’ve never heard, nor can I think of, any reason why the faster refresh rate could be worse on the eyes. It’s been universally praised, to the point that some people like rui no ona above say it makes their other devices look bad. Faster refresh rates are going to make the UI appear more fluid and life-like, and as has been mentioned is only used when needed to avoid unnecessary drain on the battery. I too wish it was on every Apple product; it’s a major draw card for the iPad Pro. But Apple hasn’t yet got every device to DCI-P3 colour gamut, so that’ll take a while. Also, the device needs to have the graphics power to support 120 Hz well. You do know that the 10.5” iPad has “TruTone” and even those devices that don’t let you modify the colour temperature in display settings?
Not for nothing, but Apple's first gen products have been by and large problem free. The one's with issues are the exception not the norm.
I disagree with the premise that the 10.5” iPad should be avoided or considered a first-gen product, but also with your statement that first-gen Apple products have been by-and-large problem free.
I and people I know have had terrible experiences with first-gen Apple products, and though I only count for one point of annecdotal evidence, you only have to read forums to get a sense of just how problematic they can (sometimes) be. I could make a huge list of such problems but recently the poor 1st-gen butterfly keyboards come to mind, as do a multitude of launch problems with the 2016 MacBook Pros, as does BendGate when Apple first launched >4” iPhones but failed to accommodate for the structural integrity required. Also AntennaGate. My first-gen iMac G5 was DOA after a couple of hours and the replacement unit, though working, was a POS. My brother’s first-gen rMBP had to go in for numerous repairs for things like a display with image-retention and later a complete logic-board failure. I could go on and on and on.
In contrast, my last-gen 2015 MacBook Pro was a dream machine and problem-free. There are reasons to be skeptical of first-gen Apple products. Apple likes to push technology to the market quickly and let its service and support take care of any higher rates of failure and other problems. These tend to settle down over the course of the first generation but sometimes require a major revision to change components and design, or even several.
I specifically stayed away from the 2017 10.5” IPad Pro. Because it break a cardinal rule of Apple products which is Never Buy a 1st Gen Apple product. And the 120hz ProMotion was exactly that. It exists no where else on any other product and you know Apple is improving it. I like the smoothness but so many different devices at different refresh rates messes with you.
I think Apple has done far more advanced stuff with the display controller on the iMac 5K. I wouldn’t worry about 120 Hz being relatively rare. I’ve not heard of any problems.
