I put LED taillamps and turn signal lamps in my FEH about 1 year ago.
Have had no problems whatsoever... except due to the very low power draw ( my goal ) the FEH constantly thinks the turn signal lamps are burnt out... but not the brake lamps! They work fine, I just get a "check turn lamps" message once each key cycle.

Red or Amber were about $7 each at superbrightleds.com

-John