I would like to echo Slunter's point on the additional filters for ranking.
One of my favourite item ranking sites has a nice set of options for what to show in the comparisons. I assume you are aware of it but incase you aren't:
Loot Rank.
Would it be feasible for the currently selected item in the spreadsheet to be shown for ease of comparison in the results? Or have a Delta DPS column comparing with the current item?