jackplates

I am looking for suggestions,pro or con or any info on jackplates.I am thinking of buying one for my boat,in hopes that I could keep my boat on plane at a slower speed or trim motor higher when on plane, as I run a lot of shallow water in miss. river. My boat is a 16foot lowe roughneck with console,will be installing a 2008 50hp.efi 4 stroke merc.possible 4 blade stainless prop. THANKS for any help