That's exactly where it's great. You effectively get in and out of it once. One preflight, no aircraft swap, done, go to the hotel. You sit there for 5 hrs and read. Yes the seat is tight but you can recline enough for an overhead panel inspection. Yes it's loud, but wear good earplugs. If you need to get up then set up a break or simply stand in the back and stretch.

Having said all that, there's no doubt in my mind the margins of safety are reduced on the Guppy vice the Bus. Not trying to be dramatic, but take the often cited example of LGA (or other short runway) with runway contamination and gusty winds, etc. There is no doubt your chance of a runway excursion will be greater with a –900ER than any Bus variant.