If the bank says it is the same card, it is probably the same card... they just named the account differently. A product change will usually retain the same account number, or a new account will be created with all of the previous history and the old removed completely. Either way, this has no effect on credit scoring unless other aspects of the account (such as the balance or credit limit) also change. BoA will probably update the balance with your current balance if they change anything.
If your credit limit is $5k+, you should be able to request a Visa signature. It will have all of the same benefits from BoA, but also include some extra Visa Signature benefits such as warranty coverage or rental car insurance.
EX:694 TU:744 EQ:777They should be able to do it with the same card number, but you will have to request a CLI first. You will take a HP for this. If you are willing, call them and ask for a PC to a Visa Signature version of the card and state that you are willing to request CLI to meet credit limit requirements. The $5k is a hard limit recommended by Visa and is the cut-off for nearly all big banks.
Whether it is beneficial to have multiple signature cards depends on what your other cards are and what you use them for. Does your other signature card offer similar benefits to the cash rewards card? If you think the extra visa benefits are useful to have on that particular card, then you should request it. It doesn't cost you any money. In this case, it does cost a HP on your credit reports though, which is not really a big deal, but pointless if you don't use the extra benefits.
You should be able to request a product change without a hard pull. The only reason you would get a HP would be if you were asking for more credit or trying to open a new account.
