We actually did quite well for lakers while using leaders this past spring.  In the past, I've gone without, and the pike always made me pay for it.  But this year, we used wire leaders and it didn't seem to affect the bite at all.  Toward the end of the trip, I got greedy and took my leader off.  Yup- Mr. Toothy came and took my blue/orange husky jerk that had accounted for dozens of fish.  

If the fish were pressured, the leader might lead to less bites. But we didn't have that problem.

Mark