Prepare the grill for direct grilling over medium heat.
Combine the golden balsamic, lemon juice and 6 tablespoons olive oil in a 5-quart mixing bowl. Whisk until thickened. Add the cucumbers, tomatoes, onion and feta. Gently fold together, being careful not to bruise the tomatoes. Set the bowl aside at room temperature for the time being.
Lightly brush the corn with olive oil and sprinkle with salt. Grill over direct heat, turning as soon as each side is marked by the heat.
Remove from the grill and let cool until you can comfortably hold onto the stalk ends. Cut the corn from the cobs and add to the bowl. Gently fold together and season to taste with salt and pepper. A generous amount of salt will likely be needed. Cover and refrigerate for 1 to 4 hours before serving.
