Your opinions please...

As mentioned above, I am an additional card-holder on my gf's Premier Duo card. As her 3-month bonus is almost up, I am considering whether to start my own card. With an average spend of around £1,000 / month, the numbers seem to be as follows:

£3k spend
Duo: 3k base earn + bonus = 15,000 Avios
Premier Duo: 3,750 base earn + bonus = 37,500 Avios

Difference: 22,500 Avios for a fee of £50, as I presume that Lloyds TSB won't refund it pro-rata as AMEX do. So, is £50 worth paying for 22,500 Avios? My feeling is no, but I'd like your opinions.

[FWIW, I've also got a BA AMEX which will be brought back into play after the 3-month bonus anyway]