By my calculations and happy to be corrected would the sweet spot for Silver be 4 Sector CE BAH exRUK via LON. Which would yield 700 Bonus points per trip. If you did 6 in a year you would need a spend of £3,300 for Silver with the 4200 Bonus on Top. So an average of £550 a trip. Which is doable for a range of locations.

Would this be the cheapest route to Silver under the new system purely on BA.