Need advice from Engineers who are also TI users

[Ask Mait]

Hello everyone,
I am a structural engineer and need your help in choosing a calculator for my work. My use is often limited to general math and unit conversions, neither I need to graph anything nor I need to program something in a calculator. Those needs are best served with commercially developed softwares installed on desktop and laptop. So far I have used some models of Casio scientific and also the HP-35s, but one day I tried my daughter's 83+ and immediately fell in love with that because of its ergonomics, feel of the keypad, and the multiline display. I find that TI graphing don't have as many direct mathematical operation keys as I can get with Casio (a big drawback) but it saves my work before auto-power-off, has rubber studded base that hold it in its place on my desk and doesn't tend to slide off when in use.
So I started finding the most suitable TI calculator for me, I learnt about more advanced models like 84+, 84+CE, Nspire CX and 89. I even bought a used 89T but didn't like because it has even fewer direct math operation keys, probably it is for dedicated programmers which I am not. Saw the 36Pro at staples but with its galvanized keys and roundish corners, found it is too ugly to my taste. Came across this (attached) comparison chart from TI website but could not understand few things on it. Wondering if some of you could help me understand by answering these questions:

1) why are 83+, 84+ not advised for any engineering applications?
2) why is 84+CE not suitable for Electrical Engineering, but good for other eng. decisplines?

If this is only due to the compatibility with running some apps, then any of these could be ok for me because the only app I could use is the unit conversion from imperial to metric and vise-versa.

Much appreciated is your patient reading and your advise if I could get.
Thank you very much

Mait