If the merit scholarship is not very critical for the affordability and you absolutely want to attend that school, then you should apply ED. If not for either point, don’t. The withdrawal from ED agreement for insufficient aid is a safety exit for you rather than an open door. There may be other consequences depending on your school policy. Also, you do not have the opportunity to compare financial aid packages with other schools. The chance of getting merit scholarship at any competitive school is next to impossible. If the school is not competitive, you are not likely to apply ED anyway.