It would be very welcome to increase farm profitability but that would mean increased food prices, previous payment schemes have been based on the area of crops grown ensuring a better farm income and maintain low food prices.
Now we have a system where low food prices are supplemented by environmental payments, because crops are grown at a loss, income can only be maintained from environmental schemes.
This means that large estates with high overheads have put the whole acreage into long term environmental schemes and don’t produce any crops or livestock. Going back to a production based system would stop that.
As for comparability with the EU the main obstacle is they would insist on supervising the UK rules, maybe in the future but not for some time yet, some EFTA countries like Norway farming is excluded from CAP.