I've just downgraded my premium BA amex. I'd not spend enough to get a 2 for 1 for two years, so 500 quid wasted, and I booked my 2 for 1 from the one earned before, and the £1700 taxes for the few F over/J back booking was by no means a bargain. It was a struggle to locate any F seats even a year in advance and the J ones, well, I've done ex-DUB ones for not a lot more than those taxes (if you price in the avios spent, and what the seat bookings would cost from the silver earned).

On pricing the £575 on the BA Amex, it depends on what you want.

1) The Insurance on the Plat is very good, though you have to use the card to book it (I know the BA premium amex has insurance too, but I don't think on much). I'd value that as £200.

2) Two Priority Pass cards have very varying value, a couple of ex-DUB (return) priced around 25 per visit would make it about 200 quid value. If you fly more than that (without BA status), or use non BA airports, then this can have a LOT of value to you. I did Hamburg from Birmingham for six months weekly, and this more than covered the prices.

3) Eurostar lounge. I like this, and no other way in apart from regular visits to get carte blanche card, or pay 600 quid return/ So a couple of them returns with partner are probably worth around 200.

4) Local and overseas dining credit, £150 each, £300 total. Not the places I'd typically eat, and often would have to go our of my way, did a posh restaurant in Antwerp, but in Germany, one of the chains Alex, takes it, so it got spent well this year on our trip.

5) £100 of Harvey Nichols credit, 2 x 50. I used it to buy overpriced tequila, so kind of used it.

6) Hotel status cards. Hilton Gold (I've had upgrades, executive lounges, this was useful), Marriot gold (not used it, apparently less good for upgrades). Melia gold (not used it). Radisson gold (useless for me, the upgrades did not bring the lounge, so really were the same room with a nicer coffee machine).

7) Amex Centurion lounges. I've found these quite nice when they've got one, a step up from the Priority Pass lounges, often in the US, in an airport which tend to lack PP lounges.

Other things, Fine Hotel and Resorts, not found anything cheap there, not my sort of hotels. Good if you're wanting a 500 quid a night hotel. Delta lounges in US (never been in one, but heard not great lounges). Special events (never used one); I think new cards are getting £200 amex credit first year too, I didn't.

In recent times there has been regular spend over £300 get 50/100 back on Marriott, IHG and a few other chains. But they've not always been there.

The points for joining also count heavily too in cost, however you value them. Consider though, whether you will hit the minimum spend conditions to earn them.