I dabbled in piano as a teenager as I was a Jerry Lee Lewis and Ray Charles fan... I still am.
Anyways... it was the early 80's and digital (sampling) pianos had just come out and my mother suggested to get one of these (because one can turn down the volume, Ha!). The piano store also had a Wurlitzer 200 series standing around. I immediately gravitated to that thing.
I was then told that, while pianos are tuned basically "ET"... they would be somewhat "stretched"... meaning that the lowest and highest registers would be a tad sharpened, so they would stand out clearer. There are btw, MANY piano tuning schools, ideologies and styles and a long history of tuning development. I was then and there also told that electric pianos like a Wurlitzer or Rhodes were tune "straight" 440 reference ET. No "bend".
The sales person claimed one could hear that. I just felt that Wurly sounded much cooler and claimed that I could hear the "fakeness" out of that Clavinova (which I really believe I can). So, I waltzed out'a there schlepping that Wurly. I regret ever having sold it, but now I got a mid 50's one with the tube amp and it just plays "What'd I Say" by itself... almost.
I discovered "JI" long before I even knew what it was or really understood that there were different ways to tune and how or why.
When I got my first non-pedal steel, I tuned to an electronic needle tuner.
Somehow, I felt that I could tune the steel "better" without it... but the tuner would then read me "bad" tuning. So, without knowing I was tuning "JI" very early on. I must still today say, it's one of the "OMG" charms of steel guitar.
It took even many of us here on the forum many years, debates, insults and even death threats to finally learn WHAT was going on in JI and in ET and why PHYSICS an NOT "our ears" create the need for JI... but math the need for ET.
Imagine a JI fretboard (which key would you fancy to play in today?

)!
When around 2001 I pretty much left "steel guitar" in my rear view mirror and then went to guitar, I could for quite some time hear that "stress" from the ET harmonies. Playing mostly antique French acoustic steel string guitars from the 30's thru the 70's... most made by Italian violin luthiers, I used a tuning technique I used to use on steel... tuning intervals at the 9th fret... so, that I'd get a tuning that was pretty much constant within my playing range (I still tune that way on the PSG now again).
I got several pianos in my houses and I really got used to the sound of ET... but it needs to be in tune!
So, coming back to PSG now just over 2 years ago... it was initially tuned E9/B6 universal. I immediately fell back into tuning JI. JI is sooo addictive, I think even someone who never dealt with it will get hooked on it on first trial!
But I could NOT get used to the "conflicts" and "mushy" chords from stacked changes. It makes me gag... physically! I can't stand it.
As I decided that my E9th times were over, I just tried to stick to ET.
I tried B0b's application of the Meantone tuning, and at first, I felt "oh, cool!", but as warned by B0b, I hit a huge conflict here and there. And evidently, on an instrument that modulates by the simple nudge of a metal bar to one or the other side, it's not just G#/Ab... it's EVERYONE of the 12 available degrees which can be a off by a 3rd of a semi-tone. Some pedal/lever combinations will just not work.
What I did was, to "study" a LOT on the piano. My then 9 year old kid was just starting, so I need to learn and experiment with things so I could show him and get started. And I used the piano to get my ears "in-tune" to the sound of ET.
I now feel "in-tune" playing my C6th ET. It's MUCH easier playing to rhythm tracks which are often in "absolute" tunes as most are now electronically generated.
Evidently, one still has to play in tune, and it's NOT all about playing with ones bar "straight"... actually, just like BE and LG often were quoted to have suggested, you need to know your "spots" and intervals you need to adjust for strings reacting differently to bar pressure (string/scale intonation)... one more reason why I tune at the 9th fret.
But playing in tune goes further than that. You may find bands with single-note instruments (winds) which will as a group form chords.... SOME tune amongst each others differently than others, and that depends much of what other instruments they are playing against. The steel player HAS to compensate to fit in (only the keys player cannot). Bass players, are a constant "issue" and often face the wrath of everybody for allegedly not playing in tune. And it IS painful when it indeed is the bass which is out of tune... EVERYBODY "fludders" until the bass player is being taken into the back alley.
JI players have to find a "golden medium" to fit in against a majority ET environment too.
and now I am not sure anymore what I was trying to say... J-D.