I've noticed that most of the folks are intelligence or ISB as well. Personally, I like playing Nyase as the ground pounding army Col. However, I beleive every banch has their own forms of intelligence.
Such as army intel and navy intel. One's going to be focused more on one thing than the other. ISB Covers everything I belive. With each service having their own branches intelligence, the ranking system would be the same for them as the rest of the members of their branch. Thus, a Staff Sgt. in the army intelligence would be the same rank as a staff Sgt. in the signal corps. The only real differnce is, one gets treated with a little more suspicion than the other. After all, he's intelligence, and they're always snooping around for something.
The main problem with rank that I've encountered, is that everyone seems to be a Col., or they think they can command troops and make demands at the lowest Non-com level. I've had several Staff Sgts and even lance corprals try to commendere my men and order me to stand down on several differnt occasions.
Another problem is female and alien officers. Everyone knows that the emipre's military was both sexist and a bigot. Adimrals Dala and Thrawn were the exceptions, not the rule. If anyone recalls, Dala was promoted in secret behind the other's back thanks to Tarkin. Even Thrawn's promotion to grand admiral was done in secret.
I've just gotten into the habbit of blantently ignoring all request by female officers and/or questioning their credability. As for none humans, I've pretty much just come up with my own 'Imperial none human brigade' of which all none human military members belong. That way, they can have their rank and what not. Yes, they may be a Colonel, but based off what 'branch' they're in, a human officer will always outrank them.
At anyrate, I'll have to look into it more. I got my wizard of the coast books back in, and they had some good information in them.