If they're telling you that they're doing a credit check and later closing your Green, that's not an upgrade/product change, that's just getting another card. CARD act regulations won't let issuers increase fees on a given account for a year, even if it's something a customer requested. This is opening a new account entirely. I considered doing this to go from BCE to BCP but it was enough of a headache getting the former, so i'm holding off.
A true 'upgrade' is something that would be offered online or requested after a year, and would keep the same card number, presumably, along with keeping the account age.
If you've only had it for a month and have had a decent file, it shouldn't hit too hard and bounce back quickly. As an existing member, it also won't be a hard pull if you're declined; however, it also seems that the charge cards don't vary in underwriting requirements, only annual fee. (ie, Gold and Plat are more exclusive not because you need better credit, you just need to pony up more every year) So you should be good to go with the Gold if you got in with Green.
I'd say go for it. The Green is a dinosaur, only there for nostalgia; there's a lot better out there for $95/year.
