I have the 100gr CX XT 4 blade. To me, they're just as sharp out of the box as my Silver Flames. Crazy sharp.
I believe Jim Belcher has been using the F-15's and raves about their performance.
I'm going to try some in either 100gr or 125gr with my mid-40's Toelke Classic Whip's and Grizzly Stiks with the brass insert.
Try different searches, because they've been discussed more here and more recently than that.
If out of a bow mid-40's and up, I think they'd be incredible. They are actually more like a Steelhead Phathead in size and are smaller in person than in print.