Well, as to 'the branch of warfare' - you're not actually in a warfare branch, your an OM. This is where your main issue lies, your an OM doing warfare stuff not 'warfare' doing OM stuff, even if it does have a nicer sound to it
I know of the changes, still doesn't appeal to me. However, your specialisation is actually the (W) part of OM, remember you're an OM first and and OM (W) second. Incase the friendly guys at the AFCO forgot to tell you, the big wigs may change your job name, and role as and when they like, even once you're a qualified OM - which is what you will be.. not 'warfare'.
As to specialisation, in order to go UW you need to fit the UW criteria, thus a more 'specialist' job, it involves getting x-rays and stuff which you don't require to become a skimmer.
Umm, put people down? You're sucking up everything the recruiters are telling you. Their job is to get people through the door, which may involve a little 'selling' of the trade, making it sound glam etc. As to bursting your bubble, well would you rather join up - get past your 6 month point and be stuck in a OM's job not enjoying yourself for a few years thinking 'this isn't what I signed up for'? Or find out the truths before you join, and make a decision on your career so you can actually go and enjoy it, or atleast know what your letting yourself in for.