**I thought originally that Barclaycard was giving higher limits on the card now, but creditboards suggests that the CLs aren't changing - just the World vs. Platinum criteria. It used to be the case that any SM under $5k was Platinum, but I think all new SMs are now World (even under $1k). The main differences are that World (and World Elite) MCs have higher fees for merchants and generally have a soft CL - not that anyone would really need one on SM.
So a $10k CL is perhaps a bit surprising. I don't know if her being an AU helped.
Also, I've used SM pretty much exclusively for 5% stuff (ignoring the bonus, I probably average like 4.75% cash back on it). They haven't given me any AA, but they haven't invited me to participate in any promotional rewards programs, either. Maybe off-category spending will encourage them to include you in the promos, but I don't know. I'd just focus on using it for 5% stuff, and accept any promos if and when they come.
I've also had my share of new accounts, which they generally dislike.**
I've found it's a bit immaterial with low bonus caps, though. Sallie Mae probably beats the Banana Republic Visa for V/MC-only merchants.
Barclaycard does take their time in putting cards in the mail. Expect it to take 7-10 days to arrive, or whatever they said.
They'll email you about one day after they mail it to say it's coming. I got the Platinum version (perhaps because my highest then-reporting CL was $2k) with $4.5k in 8/14. It's purple and even uglier than the World version.
As far as annual fees, nerfing, and MRs..it's a risk. EDP seems vulnerable to nerfing, but a PC to ED is a good option in that case. I don't use Sallie Mae much, but I do keep it open. It's also a nice SD/backup card in case I lose my wallet (locally).