I think a great rule of the thumb for the whole terminology arguement is in fact sexuality and the word transition together. For the record, sex and gender is used interchangably, sex usually being used in more formal areas for some reason. I see its usage pop up for gender a lot. o.o;
Anyway~ Transexual: We have a body gender, so sexuality will be heterosexual/homosexual according to the from/to of the body. The mind comes into play and shifts the situation because it's the opposite gender. It transitions from a homo/hetero situation into being a hetero/homo situation respectively for the individual.
Transgender: The mind is off the body's sex, so it's a transition-ish kind of thing, but whether sexuality is put into question/reverse is not considered, therefor it is an apt umbrella term.
I think that's a really good way to think about it, and IMO clears a lot of questions. Now, the idea of if a post-op is transexual. Well, yes, I seriously believe so. Why? Simple. When you say 'cis' or 'trans' it's always about the physical body's birth. Can anyone post-op seriously say they're cisgender? That doesn't make sense at all, because the quality that's always been argued that the only thing that makes a cisgender different from a transgender is that they had a natal birth of their gender o_o; But the two terms are the only terms we have to work with. There was a transition of the situation in the first place, so a post-op is closer to the criteria of transsexual...thusly, the person is trans still. o.o;
"Oh hey! This is in our past!" Oh...well, ok. Fine. o.o; I can understand this wasn't something you went through all for nothing. If you REALLY want to dump your past stuff, then we have an identity for that still. It's simple.
Woman. (Or man, respectively) Ultimately tran/cis is just about dealing with the past, so they're qualities from the past. If you want to refer to only the present, it's only appropriate to say woman/man respectively, not tran/cis/omegeaigol/whatever.
If you want to argue about non-ops and pre-ops, I have a big problem with that. Simple, transition is an incomplete process. SRS does NOT give you a full, naturally your body naughty bits. (Especially if you're FtM) As seen in understanding what exactly the naughty bits of a SRS patient is, it is 'the best we could do' literally. If a pre/non-op cannot dismiss them in 'that they are not a woman', I not only find it a snobby nobleman thing, but also fridge logic, because that gives SRS patiants no room to stand on themselves. :\
That's just how I see it, I apologize that I do not actually mean to offend anyone...I'm just...trying to state my understanding of this situation and figuring out how it can be seen to with updates, S: because I"m getting quite confused here about it all...