As I was researching this card I was told by an Aer Lingus agent that economy tickets booked via the companion voucher are not upgradeable, via either cash or Avios.
This makes the prize not worth the chasing. Spend $30k with this card and get an economy ticket worth maybe 33k EI Avios or perhaps US$600-700. Spend $30k on the British Airways card and get a Travel Together ticket which, when redeemed for business class travel, can be worth 220k BAC Avios or US$8,000+. More for F if you can find it.
Beyond the generous signup bonus and priority boarding, what sense does the Aer Lingus card make stood up next to the BA one?