That's not my opinion. That's the opinion of id Software which they articulated last year at QCon when they
mentioned the XBOX version might be getting extra compression to get smaller files:
They're talking about the decision to go 2-disc on 360 there - particularly to assuage the fears of 360 owners who may have been concerned that there was going to be an appreciable IQ loss due to the decision.
Yet that was QCon last year, and now we're hearing that they are still working on extra compression methods to try and get as much quality out of a 2-disc release as they possibly can (and laudably so).
So my point is simply this: They don't yet know qualitatively what that difference is going to be. The simple fact that they are working on extra compression methods right now suggests that it's not yet where they want it to be, and they are working on improving it. Therefore, the final difference between the 360 data set and a potential PS3 data set is unknown, and therefore the decision over whether to use the 360 data set or generate another one for PS3 is not going to be made until the final 360 data set quality has been determined, supposedly in six months or so.
What they said they want to do last year doesn't really have much bearing on what they manage to have done six months from now, other than to assure that they think it's important to work on it and are putting significant effort into doing so, so we can likely assume that whatever the situation is in six months, it's about the best they could do given the constrants. We'll have to wait and see where that is, though, and so will they.
You're still comparing BR transfer speeds/seek to DVD values. That's not what the decision is about. XBOX has smaller files because of the storage limit. PS3 benefits (according to id) of smaller files too because of BR speed. IF the xbox quality is good enough then _the same process_ it's good enough for the PS3. Once again, same solution for two different problems.
I think streaming times will be the crux of the decision. Like I said, any media benefits from smaller files.
The 360 version will be squeezed into 2x6.8Gb. That has particular ramifications on the "access time" to retrieve any particular piece of data as it means full surface coverage and DL media, and results in particular seek times, potential layer changes and transfer rates, and of course the extra decompression algorithm running once the data comes back from the optical drive.
The decision for the PS3 version is whether or not to use the same dataset or to generate a new one. In the first instance, the quality will be identical, but the data set will be smaller (no data replication as needed to minimise disc swapping), and the media will be SL and have a much smaller surface coverage, resulting in different characteristics for seek time and transfer rate, but with no possible layer change and of course the same extra decompression requirement, albeit running on a different architecture so that may vary in cost one way or the other.
In the second instance, they increase the data set quality but also it's size, resulting in increased seek times, transfer rates, but possibly avoiding the extra decompression step over the first instance.
So the decision as I see it is whether or not the quality difference is large enough with a similar average data "access time" for the data so that the gameplay is not affected. There are way too many variables in there to make a judgement on this at this point - not least of which what the two quality levels may be, but I see the characteristics of the data on the media and the drives themselves to be an important part of the decision.
If you don't take the media and drives themselves into account, then you're saying that yes, smaller files are a benefit, but you have no basis for comparison because a smaller file on one media may very well be slower to read than a larger file on another media.
HDD caching, recommended HDD installs/copies or even mandatory installs are possible factors too - but don't apply to all gamers unfortunately.
Which should tell everyone that thinks they are "porting" to the PS3 that id is in fact, looking out for the optimal path in performance/quality for all platforms, don't you agree?
Well yes, that's exactly my point, and exactly the reason I wrote it in the first place