IL is a direct delegate election which is virtually the same as winner-take-all by district. LA is proportional for candidates getting over 25%. Every state has its own rules. Obviously winner-take-all rules of any form mean the winner gets a lot more spoils.
If all states were proportional, it would be basically equivalent to letting the popular vote decide the election. Here is the current % breakdown of popular vote:
Romney: 40.2%
Santorum: 27.8%
Gingrich: 21.5%
Paul: 10.5%
If all states were pure winner-take-all, here is what the delegates would be now. Romney goes up, but Santorum goes up more:
Romney: 625
Santorum: 409
Gingrich: 101
Paul: 0
The current actual delegate counts on RCP:
Romney: 560
Santorum: 254
Gingrich: 141
Paul: 66
One more change though, that hypothetical WTA delegate count still had delegates removed from the penalized states who did WTA too early this year. With those penalized delegates put back in, the counts become the below. Romney is helped out a lot by removal of that penalty. I think that change would raise the threshold to get the nomination to 1,127 delegates:
Romney: 746
Santorum: 409
Gingrich: 126
Paul: 0