We at CNMAT passed on the UDOO because of the IO problem Paul mentions.
The designers are in a bind. To deliver on the buzzword aura of
Android, Rasberry PI and Arduino they have to make it shield and IDE compatible which means thatthey can't use, for example, SPI
as the interprocessor communication.
They seem more concerned with making the I/O pins switchable between the processors
than making the shield interface 5V friendly as these folk have done successfully (
http://www.digilentinc.com/Products/Detail.cfm?Prod=CHIPKIT-MAX32).
The fastest interconnect is likely to be the OTG USB mode:
http://www.kickstarter.com/projects...x-arduino-in-a-tiny-single-board/posts/456046
The problem Paul mentions with the serial side (too little buffering) has a big impact on the other side. UNIX inspired operating systems have to work on relatively large buffers of data to be efficient because of the cost of context switches. Stalls from the Arduino side will really impact application performance significantly. A few operating systems have addressed this, notably SGI's defunct IRIX. It would appear that OS/X Lion
may be using similar techniques to SGI IRIX (user space buffering and lock-free access to driver) as Paul has shown good performance for small write's in his benchmarking.
As Paul notes there is a long way to go before the Due software delivers the performance potential of the processors. It is possible they have raised enough money to work on this and improve the Due as a result. It is also possible the Due itself may fail. It is in many ways an "odd bird" in the Arduino effort.
Several things about the Due work against the Arduino philosophy of an easy entry point for newbies. It has two USB ports and it is not obvious even for experts which one to use. It has another shield interface incompatible with most existing shields. It has a fancy feature to help shield builders manage the 3.3v/5v issue but I can't find many shield designers who do a second or updated shield design - they usually move onto something else. The software for the Due is forked awkwardly which makes it quite a hurdle to port libraries too (or in my case write a new library for). All these are soluble problems but what will happen probably depends whether users and developers will run toward the $60-150 price point or gravitate around $20. Since I have to equip teaching labs. and spend taxpayers money to do it, it really makes a difference whether it is 60x $20 or 60x $50.