COTC is worth getting if you want pretty good, clean studio recordings of the B-sides. The version of "Don't Look Past Me* is pretty solid and crisp, and IMO, the FII B-Sides sound much cleaner/clearer on COTC than they do on their counterparts on the FII Demos.
I've spent a $#!T ton of money buying many of the DTIFC CDs and DVDs over the last 2 years, but I feel like it's worth it.
The only ones I don't have are the first two (96 Christmas CD and the Making of FII, which got re-released though YtseJam Records anyway) and the last one (Progressive Nation 2008), but I'd have to say COTC is definitely the one worth shelling out the most money for, next to perhaps Scenes From A World Tour, OLALT Outtakes and IAW 15th Anniversary. I also really enjoy the Graspop Festival, with one of DT's heaviest sets at the time!
-Marc.