Orlando real estate agent wrote:To be honest the only difference is flexibility that I see and I don't need that. When I tried to upgrade from economy to premium economy it would have cost more than the lowest premium economy fare which is all I needed as flexibility isn't an issue for me.
There are many many users who have differing experiences to you. Yes, if only the very highest economy fare codes are available then it might be cheaper to buy the cheapest PE fare, but the majority of times if there are L fare codes available then it is significantly cheaper to buy that and upgrade with miles rather than buy a PE fare.
Of course also miles can be used to upgrade an economy fare to UC, which is where the really big savings can be made. I know personally I have saved many thousands of £'s using miles for both PE and UC flight rather than just buying the cheapest tickets in those classes.
As others have said, it pays to spend a bit of time fully exploring and understanding the rules of each fare and how to make them work with your miles for you. There a huge savings to have if you are prepared to put the effort in. Of course some people arent prepared to do that, but the option is there if you want to use it.