I always search on incognito. The prices seem to always be on the higher side. In most cases around 5-10% higher, which negates most of the returns gained in the form of miles. Most major airlines like Etihad, Emirates, British Airways, Qatar, etc. do not charge convenience fees when directly booking through them. So far I've been charged convenience fees only from Indian Carriers.
I do not hold the M4B. For M4B, booking through traveledge is the only way to get the maximum reward.