A press release a while back said the 107 can burn dual layer with just a firmware update. Wether or not a firmware update gets released is probably a matter of $.
Does pioneer take the time and effort to add that feature, or do they try to encourage people who own a 107 to buy a new drive?
Even if they do release it, quality and speed of burning dual layer could be an issue.
I think what it comes down to is Pioneer has a tendency towards high standards. for example not being able to burn media certified at 4x at an 8x speed - I see that as a quality assurance issue.
I think owners of a 107 drive are very lucky if dual layer support gets added. I know I bought my drive with that in mind, knowing also that pioneer never spefically said they would release such an update... it was more a matter of a prototype and proof of concept.