From IGN’s Halo 4 Wiki"
FROM AN INTERVIEW WITH HALO 4 SPARTAN OPS DESIGNER DAVID ELLIS
We can’t imagine anyone not starting out by spending a lot of time as a Pioneer, and not just because it’s the only other Specialization that everyone will have access to on November 6. Simply, the Pioneer’s Fast Track mod nets you experience points towards the next level at a higher rate, bringing you closer to your high-level goals.
Contrary to promises (nice to know we can trust them to give out accurate information), only two specializations were are actually available to people who don’t have the LE, which is back in stock, by the way.
So if you have the LE, you can choose any specialization once you reach SR50, right? Otherwise, when do you get access to the others? Thanks.