Bottom line is that there are substantial risks in consolidator tickets, not the least of which is that they generally have $0 value with no credit if cancelled and are completely unchangeable. There is a reason that they are cheaper and they represent good value to some people.
But, it sounds as though you are looking for a trouble-free trip. Put simply, book either through DL or through a reputable TA whom you or others you know and trust regularly use and who have a physical office where you live/work.