> Personally, I's settle for a Titan derived processor without Fast14. At 40nm
> it might scale fairly well. Even a 1.8 Ghz variant could be much more powerful
> than AMCCs current line.

While the APM83290 was supposed to run up to only 1.5 GHz, the Titan core itself was announced to scale up to 2.0 GHz. I expect a Titan replacement core to not undercut that figure, and the Titan replacement core based processor should really not undercut the 1.5 GHz figure of the APM83290. So yes, 1.8 GHz would be fine for the processor I guess, and you're right that it would definitely be much better performing than anything they have right now, be it officially announced or sampling or in volume production.

> Until we see first hand the floating point capabilities of Freescales planned
> e5500 core, the (DMIPS) disadvantage of the Titan (or its successor) may
> not be as great as we're assuming.

I really don't get your point here. The DMIPS per MHz figures of both the e5500 and the Titan are officially known: 3.0 vs. 2.0. That's 50% more DMIPS per MHz for the e5500. So to get on par the Titan would have to be clocked 50% faster than the e5500, which it is not. Quite to the contrary, the e5500 is announced to scale to a 25% higher clock rate than the Titan (or even 47% if we look at the announced processors based on the cores). That's a 87.5% higher DMIPS performance altogether for the e5500 (and even 120% higher on a processor level).
Of course that's all assuming that the Titan replacement core will deliver the same DMIPS per MHz figure as Titan, which would be the case if it's really just a shrinked Titan without Fast14.

> I could see a 1.8Ghz "Titan" based motherboard [...] as an alternative to a [...] Mac.

An "alternative" to a G4 Mac as in "similar performance", yes.