What if Gangplank's E applied Fear on enemies affected by his passive debuff?

This would give him hard CC, thus making him a little bit more viable as a toplaner (or as a champ xD).

I thought the Fear duration might be 1 sec for 1 stack and 0.5 more secs for each additional stack of the debuff, up to a 2 second fear. In return he could lose the slow on his passive (since Fear + Slow would be redundant) and the E's active team buff. Perhaps the bonus MS (and, if needed, the free AD) of E's passive might be kept, since being able to skip boots on GP has always been a nice feature.

He could Q+E people to close gaps or block channelled abilities (making him the ultimate counter to Malzahar u_u), or use E during a 1v1 to gain the upper hand. He could escape ganks by applying fear on both his lane opponent (with a basic attack) and the jungler (through a Q).

A possible further outcome might be having his debuff be considered poison like Teemo, Singed and Cassiopeia's although having his E working on all poisoned (not just debuffed by him, then) enemies in range might be a little broken.

What are your thoughts? I like good ol' GP but the more I play him, the more I realize his weaknesses and I'd really want him to have some sort of viability.