It's known that there are data processing gremlins somewhere in our ARM7 core because there are definite CPU-related cockups in some Game Boy Advance games in MESS (in several games it takes the form of the software-mixed sound channels being distorted, and a few actually crash). It's just been a matter of finding simple test cases.
The Sega sound driver points software interrupts to the same "crash/do nothing" routine as the various ARM faults, so clearly they aren't using them. They're BIOS calls on the GBA though and very very heavily used there so I'm sure we emulate them properly anyway.
I haven't looked into the 16-bit samples yet, but as I said earlier DSFs once decoded are simply an image of the 2MB of AICA RAM at 0x00000000. You boot the ARM and it automatically starts playing, so there's no possibility of CPU transfer problems.