Thanks for sharing. I will have to take a look, do you detail in your post how you "cheated"? If not, I would love to hear about it. I am itching to try a board with the Freescale KL02 chip. I have thought of a few ways that I might try as you said, cheating the allowables, though not sure if they would work. For a one off, it might work.
I did a 0.5mm pitch BGA deisgn at OSH Park, but I had to cheat on the escape routing since their width/clearance rules just aren't small enough. I you find a similar service with finer tolerances than OSH Park be sure to post about it!
I agree with what you have said here about their value proposition. I just wish that I could find a similar service that would allow prototyping with .4mm BGA in a similar a la carte fashion. I cannot justify a prototype for this chip that I want to use with a board size of .38" by .38" and have to pay at least a $100 or more to do it.
I agree with your first point. The software I use is not my favorite, but until I find something else, I have stuck with it, though I am looking.
On the second point, it is hard to complain when I went into it knowing that they did not do a check on these things. If I had paid for it, that would be one thing. For me, I was able to get all 15 boards I ordered for less than $5 shipped. If I had used another service, it would have cost me at least $50 because I would have had to go to a service that could provide better design allowables.
For that, I am happy with the service that I have received and have learned a valuable lesson.
I've built quite a few boards at OSH Park recently and I've generally been happy with the results. While they don't run a DRC for you, they do provide layer by layer and composite checkplots that make common errors obvious.
I did have a problem with too small annular rings when I got aggressive with my design rules. Dan Sheadel responded quickly confirming that I met their design rules and refunding my payment for the mis-drilled PCBs. While I agree with Etmax about the risks of using untested PCBs, I've been able to prototype complicated designs (ie. 0.8mm pitch BGAs) on PCBs costing me only ~$70 which is hard to ignore.
The do give great service at a very reasonable cost. There are very few companies that offer an a la carte method of creation of proto designs with these design allowables. As you can see, they have had great service.
I agree that there could be errors such as this that could be found via many methods, and that file conversions can lead to errors, in this case it was faster to encounter the error and learn from it. As you can see, the design is quite small and I was able to salvage all the expensive components. I may have felt differently about a larger board.
While I agree that there are pros and cons to every shop that you use, I did not go into this blindly. I understood that there was no check of the boards, I did not pay for that, but at the same time, I was able to get quality boards boards for a price much cheaper than it would have cost me for larger boards. Judging by the fact that there are few if any complaints about the processes that are used by OSHPark, I would suggest that their vendor has their process well under control and that if designed within the tolerances of their process you should have no yield problems. On the other hand, if you cut into the design allowable by 33% and not expect to have any issues, then you are fooling yourself. In that I do not blame them or their process.