Originally Posted by You want to go where?
Round trip trans-atlantic upgrade from WT+ to Club World (business class) for only 25000 miles. I don't think there are any other airlines that really match this.
Not quite true. For example, the upgrade for LHR-JFK is only 22,500 with Asia Miles.
The disadvantages relative to BAEC are that (1) some BA discount economy fares (i.e., outside K, L, M, R) earn 0 Asia Miles (even 25% miles would be better than 0); (2) availability may be less favorable; (3) it will probably take longer to achieve sapphire or emerald with MPO than BAEC; (4) no status bonus with MPO if OP achieves sapphire or emerald status; (5) no chance to augment mileage-earning with UK-based credit cards or loyalty cards (e.g., Tesco).