C-2100UZ and low light

I would recommend some experiments before buying an new camera. With ISO 800 You get one step faster shutter, with ISO 1600 two steps. I believe that that is compensated by the IS, so, to get full benefit from ISO 1600 film, you should find a film camere with IS. I have not found a better film camera except in one property: the B-setting of shutter time. I can use minute long exposure times. With times less than 1 second, UZi with its IS is top class system for low light photo. I would try following corrections for your photos. Try to fly along an arc so that the you can shoot though side window or an open window but to your left or right. The arc should be flown so, that the midpoint of the picture remains unmovable in your viewfinder, (not turning the camera. That should compensate for the speed of the aircraft (i do this for day time pictures from a/c too). Try shorter exposures, in your example picture 1/20, 1/40 and 1/80. The lights are lights and dont lose anything. The only thing you lose, is the illuminated area near the foreground. That you can compensate in your pc by lightening the picture. You get a little bit noise but I believe that the result might be better than the current one. At least the picture is propaby sharper.

If you don't need a zoom, the best film P & S that you can get for what you described is an Olympus! It is the Olympus Stylus Epic which has a very sharp 35 mm f2.8 lens. The f2.8 lens with an ISO 800 or the new ISO 1600 film should fit your bill for low light, fast shutter speed photography. B & H has it for $80. Popular Photography magazine once called it the biggest bargain of all times for no-flash photography.