I see that CapitalOne Spark Miles now gives 2 miles per dollar and is transferrable to nearly every airline or redeemable for cash back. Since one cannot get cash back from AMEX Blue for business, would this be a good hybrid? I.E. just keep on amassing CapitalOne Spark Miles while always having the option to request a cash check? I find the AMEX MR not being able to be converted to cash back (not gift cards) is a negative.