From my personal view Steve I would definitely tell my wife to go for it.

The fact that this immigration journey will cost me a total of around £10,000 taken absolutely everything in including future FLR & ILR and trips back and forth to the Phils ect I think that £870 would be money well spent.

The reason for this that ILR is fine in itself but if you are ever out of the UK for more than 2 years then it becomes invalid also I think my wife having a British passport gives her total freedom to travel almost anywhere without restriction.

Also for her to be a British national same as our son would make her so happy.

Anyway Steve whatever decision you make buddy I wish you all the best...