Both designs are licensed designs: The SharkPPC is a Sonnet design. while the SharkPPC+ is a licensed IBM reference design. In other words: The hardware works, at least with a passive backplane.
The Problem is integrating the SharkPPC with a classic Amiga motherboard. By all means, that's a damn tricky job.
I don't doubt that Elbox will deliver (they always did), but "Q4 2002" sounds way to optimistic to me. My personal guess for a first release of OS4 is November 2002 (CyberstormPPC version) with the AmigaOne version following a few weeks later. Then they'll have to do the BlizzardPPC version.
Afterwards they can start to work on the OS4 version for SharkPPC. And that's going to be tricky (i.e. it won't be done in just a few days).
Elbox is just making lots of PR noise these days, because they fear to loose sales to the AmigaOne. They don't want to be forgotten in all this A1 hype.