So, the cast time on W is going away but it now has a 0.25 second delay before damage starts. In terms of how long it takes to go from cast->damage, is this a net gain, loss, or is it neutral?

Currently, the first tick of W is very useful for getting that last bit of damage onto a running target. Since, E has a short cast range and Q a long delay.

I think cast times range from .1 to .25, and I think his W is .25.

I suggest going into a custom game and casting Malz' W. Try to picture how many you could get off in one second.

Its neutral it just helps to get the entire combo off

This is neutral.

Malzahar's 'W' used to have a cast time of 0.25 seconds and the damage started instantly.

Now it has no cast time, but the tick of damage is delayed 0.25 seconds. Time from cast to damage is 0.25 seconds.

Thank you Xypherous.