1: Conroe cannot be placed in a DP setup.
Nah, really! I didn't know that!
So Apple would be taking a step back from its Quad G5 and only have Dual Processors
Uh, you realize that the Quad G5 was the highest of the high-end, right?
Throughout the G5 era there were dual-processor and then dual-core models. I know this will be shocking but there was even, for a time, a SINGLE-CORE SINGLE-PROCESSOR SYSTEM. Don't faint.
But as Anandtech's numbers illustrate, the Quad Xeon doesn't offer any measurable improvement to a dual Conroe setup in many tasks - like the memory-heavy arenas I referred to earlier.
So we just pay more - initially, for the second Xeon and later for FB-DIMM RAM - for no benefit.
2: It would not offer the stability that the Xeon setup provides.
Of course it would. Conroe systems are no less stable than any other platform. This is just a stupid argument.
If we want to talk hypotheticals, people are putting FB-DIMMs in their Mac Pros that don't meet Apple's heat requirements because 'official' RAM is too bloody expensive. This may lead to a shorter life for the RAM, perhaps for the computer - or simply a number of ECC errors in the meantime - making the Xeon Mac Pro less stable than a Conroe Mac Pro running cheaper, cooler and more usable DDR2 RAM.
3: A speed hit in the RAM area has also been the case with workstations. The workstation more than makes up for that in its stability.
This is also an absurd argument - desktops are stable. Kinda like the G3, G4 and G5 towers used for the last near-decade.
But in any case, the Mac Pro isn't a 'workstation' - it's Apple's only genuine desktop. It can work as a 'workstation' but in the vast majority of consumer situations it's going to be called upon in the exact same way G5s were before, or Dell desktops or any other machine.
A few gaming benchmarks most assuredly does not mean that the Mac Pro is a slouch.
No one suggested that it was - however, the FB-DIMMs are crippling in desktop tasks that the Mac Pro will often be used for - games, Aperture, Photoshop - compared to what the system could be otherwise.
You're paying for quad-core Xeon goodness, and paying out the nose for FB-DIMM 'stability' - but getting the performance of a dual-core system.
If I placed an order for a Mac Pro 2.66/4GB tonight for $3000 - it would perform not noticeably better than a Conroe 2.4/2.66/4GB coming in at $1500-2250. That's a major problem.
All of those points, however, are irrelevant, because you don't seem to grasp a basic concept:
Apple can produce a Quad Xeon Mac Pro for two groups (people who need it, Mac fanboys who can't help but slobber on Steve's latest offering) and also produce a dual-core Conroe for everyone else at a reasonable price-point.