- As Adywan said, it means the extras can come later and not hold up the release of the main feature.
- Best possible picture quality - what are you using to encode the video?
- Don't forget that as this has been sourced from the DVD, the video has already gone through a lossy process once, and therefore will need as much bitrate as possible to avoid concatenation of any compression.
- If Adywan does a seperate DVD-5 as well great, or surely people could just DVD Shrink the DVD-9 version?
- There's no reason for the PIF to be on a DVD+R DL - you could spread the VOBs across 2 x DVD-Rs or use WinRAR to store the .img file across two DVD-Rs.
To put the whole Dual Layer thing into perpective, it looks like the drives cost about £20 in the UK at present - the same as a DVD. Ignoring people's confidence in upgrading their own Pcs, would it be fair to say that those who have BIG TVs, and therefore benefit from the best bitrate, probably have Dual Layer Burners / the money to afford a Dual Layer burner. Those who have older CRTs who won't necessarily notice the bitrate (because CRTs usually take the 'edge' off images) and might not have / can afford Dual Layer burners will probably want the DVD-5 version.
Just my 2p worth.
PS - What are you authoring this in Ady?