I don't think there are negatives other than the $100 cost. The rest of it is just limitations (e.g., scheduling interview, not enough locations, doesn't work if traveling with family, etc.)

The only "downside" is if you like to smuggle in things you're not supposed to. If you bring in a cuban cigar through the regular line and get caught you just lose the cigar (in most cases). If you do it as a member of GE, then you get booted from the program, likely permanently, and may be subjected to fines and other penalties.