I am not sure if an IYONIX for 800 UKP now is a significantly less compelling offer than an IYONIX for 1300 UKP in 2003.
In 2002, Samsung announced that it has a 1,2 GHz ARM10 variant "nearly ready". Did this make the IYONIX a less compelling offer? No, because it turned out that Samsung just released a lot of hot air instead of an ARM that could actually be bought.
The Intel announcement is very similar: they talk about a 1,2 GHz XScale variant (which might - independant of the clock speed - not be too suitable for a desktop computer like the IYONIX anyway - after all, it won't have a lot of RAM bandwidth, neither will it nicely integrate something essential like PCI), but also say that the first offering will be sub-1 GHz.
Look at the A9. It features a 400 MHz Samsung ARM9 variant. Why doesn't it use the often-announced 533 MHz variant Samsung were regularly promoting? Because it is not available.
At the moment (and probably for the next 6 months at least), the only suitable processor for an IYONIX-type computer is the IOP333. However, from a marketing point of view, the "jump" from 600 MHz to 800 MHz is just not enough, even though from a technical point of view it is probable that it would offer a significantly better performance.
Unfortunately, the performance gap between available ARM variants and x86 processors seems to widen all the time. Which is bad news for the future of RISC OS on the desktop and dedicated hardware development.
Even more unfortunate is that the future of high performance ARM computing might be a multicore architecture, which doesn't exactly suit the way RISC OS is structured at the moment.