Oh, it's nothing against the Prophet08. When I first got the P08 it was the most important thing in my arsenal. It's just a testament to HOW MUCH the TI can do.
I would recommend the P08 rack module to people, especially if they don't have any analog in their current set up. My favorite thing to do with it is program the layered patches using the 4 LFO's per patch to muck with stereo panning. Have you ever applied an LFO to an LFO? That's an interesting effect, too...I consider my P08 to be the EFX/background pads of my tracks.
My current experiments have me layering the TI with the FR XS or sh2. I've found this combination hard to beat: you get the thin, complex upper end of a pad with the growly, dirty nastiness of an analog bassline monosynth. Again, the P08 falls somewhere in between (I don't particularly like the P08 on bass, and it is consistently outperformed for strings by the TI).