Well, here is my take...
Being chosen to be an ELT is 33.3% needs of the Navy, 33.3% grades, and 33.4% popularity contest, or at least it was in 1998.
In my class, they only took a few ELTs. They took even fewer SPUs. I had high scores, but I do not remember if I put a package in for ELT or SPU, honestly.
As soon as we got to prototype, we got the word to cozy up to the ELT staff guys if we wanted to be ELTs, and get in tight with the real MMs if we wanted to be SPU MMs. Alot of this unfortunately came down to off duty interaction (not allowed, by the way) and how many smokes/how much dip you could carry with you to dole out in the to staff in the cubes. I was married, didn't smoke or chew, and was a little too old to kiss ass, so off to the fleet I went.

I don't envy ELTs, nor do I wish to be one. We need ELTs, just like we need regular mechanics. Did I get nervous on my first actual Chief Reactor Watch when I came down to find that it was ELT proficiency night, so ELTs were on all mechanical watchstations? Well, yes, luckily we were steady state steaming

. However, I would have been equally nervous to have to draw a primary sample under the watchful eye of NRRO.
I really don't understand the debate. Is being an ELT good? Sure, why turn down more school? As far as Navy advancement goes, I do not think it is a any advantage to be one or the other. The CPO exam is no different for ELT/non ELT, and the test is much more mechanically heavy than it is chemistry/radcon heavy. ELTs who do not bother really learning the mechanical side are at a distinct disadvantage, however. As JMK said, if someone wants to make Chief, or even LDO, the EWS/PPWS qual is almost "required", and you had better be heavy on the mechanical side of the plant, since that is about 70% of the qual. Career minded ELTs who do not bother getting out of nucleonics to learn the plants are not making good career decisions.
I will say that ELT shore duty, at least in the shipyard, is a little bit of a raw deal. ELTs are almost exclusively RCTs, and from what I can tell, that is a pretty crappy job (shift work, uber-controls, high visibility, etc). This makes off duty college a bit challenging.
There are good ELTs, and there are earthsack ELTs. The same can be said for almost any category of people in the world. We tease ELTs on the ship, but part of it is jealousy and the other part is that we aren't quite sure what they do in nucleonics, but we are sure that only 1/2 of it is legal.

Post Navy, I want to teach history in a military school/academy. To be honest, not much about the technical side of my job will help me then, anyway.

Oh, what was the original question again?