My other car is a MINI!!!!
Main reason for getting rid of the pcv valve is to minimise the chance of leaks. The pcv pipe work under the inlet is notorious for boost/vac leaks, and the vacuum drawn breathing on idle isn't really needed, by fitting a catch can you're just letting the engine breath naturally. You can leave the pcv system in place and still fit a catch tank, and it's also possible to remove the pcv part of the breather system without fitting a catch tank, although it's best to do both