I was looking at booking (a reduced) CE flight LHR to PSA and cancelling my booked ET flight to PEG (where I need to be), and then taking a 3-hour train ride (yes I know, quite silly really).
What swung it against doing this was the awful timings, having to depart T5 at 7 am, versus my current booking departing T3 at 5 pm. I just couldn't forego the lounge hopping in T3.