I would like to see both - some classes could have separate power pools / spell slots / whatever the magic system uses and others use a single pool. While single pools would probably make up the majority of classes, having a few with split pools make for interesting characters.
I have in 3.5 designed a few custom classes with highly split pools and they play well in the hands of experienced, creative users although they would be overwhelming for beginning players.
I have in 3.5 designed a few custom classes with highly split pools and they play well in the hands of experienced, creative users although they would be overwhelming for beginning players.