Maybe I shouldn't have used the word enlarge. I'm not familiar with the files, but reading some users feedback, the Foveon files degrade less when enlarging, and that is why they compare it to larger mpixel sensors...If there is truth to that, then I would like to know the limit point down to a pixel level. It's not a matter of enlarging for output(thats mainly based on viewing distance). It is a matter of a workable file. A 16 bit or so meaty file that will go through agency retouchers. It should at least print 20"x30" or something without enlarging.
This is for industrial commercial photography including microscopic, etc. each detail bit counts.
You might find some info on large prints with the DP1 & DP2 cameras in Nick Devlin's field test
on YouTube (jump around 9min30s for print test). Ultimately, only you can decide whether the files are up to your standards.