Advantage of manufacture capability is I think obvious going to large-scale. Even small scale permits potential growth with the right design, useful for your own application as well as others. The world is a BIG BIG place...
This is an Arduino compatible 2313.
I am working on a MEGA32:
I plan to try the Atmel APPNOTE 305 which implements USB in assembly in the 2313 leaving little room for else. I compiled the code targeting the MEGA32, it looks do-able. AN305 provides tips on implementing it on other processors and an example ATMEGA8 implementation.
Beyond Arduino compatibility, the hardware will also support other code such as that called ILOS featured at CodeProject: http://www.codeproject.com/KB/system/avrilos/schematic.pdf
Link is to a schematic but checkout the demonstration. I have compiled it in Atmel Studio 6, interested in combining Arduino and ILOS features. An Arduino application would exist as hosted inside the ILOS.
Interesting thing about ATMEGA32 is that it is available in 40-pin DIP, well suited to hobbyists who don't want to freakout when the processor is damaged. Simply drop in a replacement for little cost, a good selling feature when attempting to appeal to multiple sets of users. The ILOS code is in C, and warrants adaptation to C++ for hosting Arduino applications.
It will take me months to put both the hardware and software together,, looking for help. I think the result will yield a chance to sell the Arduino-compatible to hobbyists. As well it will host the application I have in mind.