Duffry, your efforts are much appreciated. Thanks for inputting the time into fixing this thing.
However, here's something I found out tonight, trying to decide on which piece of 25m T9 I should go for first:
Both 25 normal and 25 heroic items share the same names, and Excel seems to either be randomly picking one of the two or always picking the Heroic version (what happened to me), which will obviously cause a discrepancy in your results and findings due to obviously higher stats from the normal pieces. I am fairly sure someone else has figured this out and reported it to you by this point, but a nice and quick fix to anyone having trouble with that is to hit the "Items" tab and modify the item names a bit. I added "H" for Heroic at the end of the heroic tier pieces I was researching, and the gear tab now picks up the items correctly.
Just thought I would share my appreciation and findings, in the hopes they are useful to someone experiencing the same problem.
Edit:
Something else that I just found out.
[Lightbane Focus]/
[Chalice of Benedictus] have sockets and, although the socket is listed in the Items tab for these items, it doesn't show up in the Gear_Buffs tab - probably because the list of OHs with slots is pretty slim and it's possible nobody has added the extra rows under the OH tab before these two popped up.