This is another one of those places where simple frame averaging–assuming your machine can hold the image steady across multiple exposures–can clean that up completely. By taking advantage of the temporal dimension we have access to (because we can make our subject sit perfectly still as long as we like), the “how noisy is the sensor” camera characteristic doesn’t impact us much.
You’d asked about noise in a different context back in August and the same links I replied with then apply to this situation, too.
I settled around averaging 8 exposures for my “high quality” scanning preset. That was used for that challenging “silhouette” shot above, where you can bring the exposure up several stops without getting any of that digital-looking noise.
The only trade-off is that it makes the machine a little slower, but that feels like a small price to pay for the extra quality…