Running on treadmill or Stairmaster, which one is better?

I have recently started using the 'Stairmaster' in the 24 hr fitness gym. Before, I always headed off to the treadmill, as I could never get the hang of the elliptical, for some reason I always felt I'd fall off! Anyways, this Stairmaster, a moving set of stairs, is darn good workout. But does it burn more calories than running, for the same time interval? My plan is to verify this experimentally, but I tried looking online too. Also one point to note, is I dont really 'run', more like a jog at an avg speed of 5mph. I found one website called nutristrategy that has some figures to compare. For 1 hour of workout, calories burnt in any activity are listed, I'm copying the ones I'm concerned with :

Activity (for 1 Hour)   130lbs   155lbs   190lbs <-- Different body weights
Running, 5 mph (12 min mile)   472   563   690
Running, stairs, up                       885   1056   1294
Stair-treadmill ergometer         354   422     518

I am not sure which row to look at for the Stairmaster machine, but it cant be the third as that is too less. I could easily burn 285 calories in 30 mins on the machine (and I wasn't doing half as well as the other people around me!) . Well, I guess I will just have to conduct the experiment ( try on both for same amount of time , though not one-after-other as that might affect performance, but on different days) and find out !