I disabled hyperthreading on the i7 and ran a new benchmark. It got slightly better on some and slightly worse on others (I just highlighted the negatives and the double digit gains). There doesn't appear to be any rhyme or reason to it either. Not what I was expecting...
Here's the old i7 results (with hyperthreading) compared to the new i7 results this makes it even more clear that it's basically a wash or maybe slightly favoring hyperthreading. Note that the spreadsheet was set to not show decimal places which explains results like scud where they both show 74 but there's a -1% difference.
I wonder if a longer bench run (like -bench 360) would show a more clear difference.