Elliptical for cross training?

I love the elliptical machine. Lately my workouts have been toggling between spin, swimming, and the elliptical + weights. The elliptical boasts a high calorie burn and great distance which is terrific and motivating ... but it's not the same as running. Here's my take:

Positives of training on the elliptical:

• Low impact - read, no damage to knees
• Easy to "zone" to - the elliptical is the best TV watching cardio machine at the gym
• Can control resistance and climb much like a treadmill
  

Negatives of training on the elliptical:

• It's just not the same as running! I wouldn't be comfortable training solely on the elliptical and then entering a trail race - if running a race it's important to train on the terrain you're running on
• I don't buy the calorie count - I love seeing the numbers climb, and I'm sure they're close, but without knowing VO2 capabilities, height, weight, etc. I don't understand how burn can be calculated
• Good for the booty, not so much for the calves - running gives awesome legs (I think), the elliptical gives a high bum, tight thighs, but only soso calves