I think this would actually be awesome for 20-60 minute sprints. The only change I'd make is to put the pairs into private offices, with comfortable room for 3 and cram for 6, ideally with glass walls or something. And then give everyone a private personal office to use for half of the day as well. When engineers cost $200-300k/yr and real estate is 18/yr/SF, I don't see a problem with burning 500 square feet per engineer.