This thread is making my brain hurt!
Lets take the extreme example:
If you played just 1 line @ 10c it will take 25x more spins to get the feature, but each spin costs 25x less than playing max lines @ 10c.
So I agree with Zoozie there - makes no diffeence.
But when you do get the feature by betting on 1 line it plays on all 25 lines, which is 25x better than free-spins with just 1 line, which you'd get on any other slot.
So surely you'll win 25x more....?
(Anyone got an aspirin?
)