Piano and keyboard temperamants

Tuning and MIDI are separate things, and, depending on the instrument, may be wholly unrelated. 
 
MIDI has no knowledge of what an instrument will do with the commands it's given. It might transpose the note, or even play a non-pitched sound effect. It's entirely up to the instrument.
 
As for why you might choose an alternate tuning, that's too esoteric a question for this old school rocker. Maybe if you were into Arabic folk music?
 
 

Although there are about thirty, it's the Equal Temperament vs Originally recorded that I am trying to get my head around. Especially as the default is not Equal temperament.
 
I had read a while back the piano tuners detune the higher range up a little, but forgot the reason for this. This isn't the same as using eastern tunings, where say every 6th is flatened, it relates to equal temperament.  But when I'll be using synths, samples and acoustic instruments that aren't raised in the upper ranges, I don't know why this would be the default for addictive keys. This is more about intonation than funky turnings.
 
Each of the Trio have their own intonations, as 'originally recorded' is different for each original instrument and they all have their own intonations depending who tuned them.  

Now that's a bit of a stretch. Better hum "Come on Eileen" like poor old Johnny Ray.

Kamikaze
Although there are about thirty, it's the Equal Temperament vs Originally recorded that I am trying to get my head around. Especially as the default is not Equal temperament.
 

My guess would be that someone would want the "originally recorded" to add the imperfections that were inherent in the classic instruments.  They would give you Equal Temperament as an option in case you wanted the perfect pitch.  As I understand it, no piano can be perfectly tuned across all the keys (although i don't see the reason).
 
I'm not familiar with the instruments in Addictive Keys, but it seems similar in this respect to amplifier simulators.  I appreciate that tube-driven Amp Sims will distort as you increase the volume (similar to Originally Recorded) instead of just getting louder (Equal Temperament).  It was originally a flaw, but one that we have come to want.

Slugbaby

Kamikaze
Although there are about thirty, it's the Equal Temperament vs Originally recorded that I am trying to get my head around. Especially as the default is not Equal temperament.
 

My guess would be that someone would want the "originally recorded" to add the imperfections that were inherent in the classic instruments.  They would give you Equal Temperament as an option in case you wanted the perfect pitch.  As I understand it, no piano can be perfectly tuned across all the keys (although i don't see the reason).
 
I'm not familiar with the instruments in Addictive Keys, but it seems similar in this respect to amplifier simulators.  I appreciate that tube-driven Amp Sims will distort as you increase the volume (similar to Originally Recorded) instead of just getting louder (Equal Temperament).  It was originally a flaw, but one that we have come to want.

Although undoubtedly These instrumenst would contain imperfections, the stretch tuning is intentional. Should have posted this in the first post really, it would have been clearer. This the the Grand, Upright and Rhodes from XLN.
 

 
 
 
 
 

Here you go Fleer, as you love those leccy Keys
http://chicagoelectricpiano.com/rhodes/stretch-tuning/

It seems that it's normal for Rhodes and Pianos to be stretched. but not a Hammond. That playing guitars with rhodes is not normally noticed, because they sit in the middle of the keybords range, where the least stretching occurs, but upper notes are more noticeable for those with good ears and bass guitars can sound a little sharp.
 
As I am not a great wind player, and the intonation of wind instruments needs embouchure correction to intonation which is beyond my skill and ear. I've been using melodyne to add a little correction. So maybe I should add more correction when notes are playing flat, or set the heads and mouth pieces to lean to the sharp if I'm using XLN's Keys with the original records pitches.
 

Slugbaby
Now when my vocals are pitchy, I'll blame the keys!  

Only when you're singing like Micky Mouse on helium, or Barry White with a cold.