BB-xm : Angstrom vs Ubuntu & GUI vs No-GUI

All,

This really is a well discussed topic and there are many resources on the web that discuss this.
After reading all of them I understand that ubuntu is slower and Angstrom is relatively optimized and hence faster for the BB-xm.
But I still cannot decide what the best approach for my application would be.

I will be using the BB-xm for a handheld device, that will capture an image (will be using a VGA camera from leopard imaging). Then there will be some processing of the image to extract some information (specifically, QR code decoding, edge detection & hough transforms). The information processed needs to be stored and then retrieved later on when the device is connected to a computer.

Processing each image should ideally take less than 2-3 s. and say a maximum of 6s. Of course the faster the better.
Since there is some moderately heavy processing to do, I thought Angstrom would be a good idea.
On the other hand, it won’t be as user friendly as Ubuntu (and I am very familiar with Ubuntu but haven’t worked at all with Angstrom). I have less than 1.5 months to work on the whole project, so I don’t want to spend a lot of time debugging either.

Also, using a GUI would make things convenient during development but would also slow things down (the GUI will probably not be needed at all when the device is deployed).

The project has to be completed in under 3 months. And I am a FT student so will have limited time to work on it. In other words, being able to develop this system in under 2 months and processing each image taking more than 6s is a more favorable option than developing this in 4 months and the processing taking 3s.

What option do you think would work best for me ?
Ubuntu or Angstrom ?
GUI or No-GUI

best regards.