Honest man, I have no personal axe to grind but I feel I should point out that Lufthansa have been sending a 737 across the pond for a couple of years now. The Globespan 737 I undertand is in fact a brand new 737-700 ETOPS equped and approved. OK its only got a single aisle but then I believe that the 707 was only single aisled.
If the loads only warrwant a 737 load then surely that is what is required or do you put a fancy 250 seater on a route that only needs a 150 seater? Then charge more for the empty seats?