I would look at your situation and the frames you are currently experiencing and based on that if you really feel that its necessary then yes it may be a possibility but my guess is adding a second one would be unnecessary for you. What does your setup look like
GPU: 1x 7870
If you have a store bought machine please supply.
Yea I would wait honestly, if you feel that your frames are suffering after a point you can then upgrade up to a CF configuration or quite possibly do to the time it would take to get there get a newer gen card.