Watching Blu-Ray or Dish VOD at 1080i60 has no resolution loss compared to 1080p24 assuming your TV does proper deinterlace for display at 1080p60, so it is not watered down. The only thing you would be "losing" would be the benefits of not having 5:5 pulldown and I'm willing to bet you would not see the difference between 1080p24 and 1080i60.
But this VOD should have higher bitrate than normal Dish 1080i programming, which should make a difference in what you see, and for the better.
Put it this way, I have a 1080i RP CRT and am looking forward to this download.....and I love Blu-Ray and it looks fantastic on my set.
And my guess is a lot of what you are seeing on the newer displays is the Motion Enhancer which gives the picture a smoother look, some like it some don't.
No go enjoy your nice TV and your Prius!