Pash posted a few comments earlier. Whilst I agre with some of them, he seems to think the low-cost airlines are totally inflexible. Not that familiar with the others, but certainly for easyJet
[1 - If you pitch up for an earlier flight, there should be no problem getting your reservation changed(inventory permitting).]. .You can normally change a low-cost ticket to another flight....it will cost you a change fee of around £25 but if the ticket is £100 less than a full service carrier then you're still in profit!
[2 - If you no-show, no problem you can get a later flight (inventory permitting).]. .Still some flexibility to change as above, depending how late you turn up.
[3 - If you choose not to travel at all, fine full refund.]. .True....you don't get this with a low-cost.
I guess it all depends on how often you travel and how much flexibility you regularly need. If you travel a lot and only occasionally need to make a change, then you're still a lot better off with a low-cost.
Q. Tarse