Mike,
I did compare 1080 i to 1080 p with similar format-ie cable tv or Blu Ray.There is no doubt that P is better(more resolution by far) but it depends on the content.From what I saw,using standard cable,the image was worse on the P version,using Blu Ray or HD Cable,much better on P-in fact,if you are using HD content,then the obvious choice is P,but for regular DVD(even with upsampling to 1080 i)or regular cable,to me,the i version was better.The dif. in price between i and p is not great,a few hundred.