The CSR is a better earning card than the UA card. Every dollar you spend with UA gets you 3 UR points which transfers to 3 UA miles. With the UA card you only get 2 UA miles for UA spend.
If you can use a service like plastiq (~3% fee) to pay your rent/mortgage on the UA card, then sure go for it. But to divert your normal spend from the CSR to the UA card isn't worth it, IMO.