Pretty smart as Win/x86 programmers still doesn't tell anything about experience of unix development.

Next thing is that the chip manufacturers are normally involved in initial porting of the low-level layer of Linux to their specific processors. If they do a crap job, the result will be crap. It isn't unreasonable to think that they would do a similar crap job with the low-level code for running Windows on that same target processor - our famous BSOD is normally (unless the hw is broken) caused by the huge amounts of badly written Windows drivers.

So yes - I have fixed a number of direct bugs in Linux kernel code. But normally not code from the mainstream Linux distribution but code from the chip manufacturer or from some consults hired by the chip manufacturer. There are also "pretty smart" people who implement SPI drivers strictly simplex - never ever thinking that a device may send data back at the same time that you send data from master to slave.

In the end, anyone who do select a hw + an OS have to make some form of evaluation of the quality of the low-level drivers for that specific combination. Especially if the drivers aren't part of the standard OS distribution.

The serious issue here is that in many cases, the chip documentation doesn't contain enough information to let you fix driver issues yourself even when you have the source code. You don't know what bits in what registers will give what result.

In the end, the weakest spot of both Linux and Windows platforms are the hw-specific driver layer. And a Windows release can get through the hw compatibility tests by just ignoring existing hw functionality. So the user will read documentation about the chip and select it because it supports a critically important function, and then end up with drivers that do not support this feature. That is a good reason for getting a reference hw platform as soon as possible to test all critical functionality on when it's still time to throw out the processor (or maybe an external hw chip) and use something else that is supported by really working code.