Specific Driving Habit Question with AT in S mode

I have been wondering if using the S mode constantly limiting highest gear to specifically maintain a certain RPM/Engine speed (rather than the highest gear itself) is detrimental in the long-run to the auto-tranny other than the expected slightly more rapid wear-and-tear on the engine and would like a scientific explanation if possible as to "why it is" or "why it shouldn't be."

I will elaborate a little background...

MPH and RPM I notice the engine is roughly capable of--I may or may not have pushed the engine to it's limits in order to gather the following information ;P
[Gear]
1st: 0-35MPH@Redline
2nd: 35-62MPH@~3600RPM-Redline
3rd: 62-91MPH@~3700RPM-Redline
4th: 91-Governor Limit 116MPH@~3800-5400RPM
5th: Blah

With that info as a base for my following question, when I use S mode I tend to rely on the -/+ to get the RPM within 2700-3100 for my target MPH instead of the ECU dictating my gear in relation to my throttle input with S mode placed in S4 or S5...example; cruising on S3@50MPH/~2800RPM, as opposed to ECU selecting [insert gear]@~1400RPM to maintain a 50MPH speed.
MPG is unimportant to me... Yes I do understand the MT is designed for what I'm doing with my AT Taco and will probably be urged or recommended to exchange my Taco... But, my point of inquiry is about the mechanical capability and limits to what the AT can handle or tolerate when user input is made.
I would like to know if the constant -/+ S mode "shifting" is bad/worse/no effect than ECU doing the shifting for me.

I am eager to know the opinions or experiences of those of you who are/were auto-mechanics/engineers! I will of course welcome all who have something to educate me with!

 

Interesting... waiting for some gearhead types to chime in. Meanwhile, I think disconnecting the governor is in order.

 

You won't hurt it. Your transmission is not what would suffer, its your engine. Redline is a number the engineers picked to keep idiots from blowing up the engine. Redline is not max it will do more than redline rpm, but, engine life will suffer so they limited it. I would say this engine could tach near 9K but again, your design life will suffer.

The only thing you are doing is killing your efficiency.

 

So it would mostly affect what I had mentioned about the accelerated engine wear-and-tear then. Yeah I am aware that a lot of are engines typically built to withstand advertised RPM thresholds. My older brother was a "Rice Rocket" tuner type and would teach me various aspects of the basic sciences/physics of motors but not necessarily automatic transmissions or those equipped with steptronic/tiptronic dual-clutch semi-auto trannys… Hence my AT S mode curiosity...my Google-ing didn't help. Haha truth be told I quit searching after like five links of non-relevant hits XD