If you need to top up your account, you'll get a better earning ratio transferring Starpoints in 20,000 - Starpoint increments and earning 5,000 bonus Miles & More miles than you will putting
additional unbonused spend on their Barclaycard credit card.
Not exact matches
But for
unbonused spend, even at the worst bonus tier, the 10k
additional spend for 25k avois, that's 3.5 x for
unbonused spend vs max of 1.5 - 2x for the transferrables.