It seems like the question is whether to hold out in order to optimize or to do ED for a perfectly very good outcome.
The optimization scenario has many outcomes, from ones that cost more to ones with the same cost. In each group, the schools may appeal more or less than Lehigh. You may want to try to name the best and worst outcomes ($ and appeal) to get a feel for what you gain and lose by pursuing Lehigh. As someone said above, this has a game show quality – do you stop playing now and go home with your $200,000 winnings or do you risk it all for the $500,000 and the trip to Fiji? As anyone who has ever watched such a show knows, there’s a different right answer for every contestant.