For which biotech company is the distinction between gross and net royalties most consequential?
Well except for your restriction to companies where royalties have not yet begun, I would have said NTII with their Namenda royalties. If I recall correctly those basically got cut in half because of royalties owed elsewhere.
IMGN might be a candidate that fits your criterion, if only because we are talking about a very thin royalty on a very big number, and so any netting would be significant.