I don't think you would go wrong with the choice of an OTO. As to changing coupling caps, this is a matter of personal taste, so be prepared to switch back if the new caps are not to your taste. My local Audio Note dealer, who also builds his own tube amps and linestages, HATES anything Mundorf. I have not done any serious comparisons myself, but he has, and does not like them in either amps or speaker crossovers. He also hates Duelunds. This is a matter of taste and system tuning, so don't expect any particular change to necessarily be an upgrade, regardless of price and reputation.
Certainly upgraded Audio Note parts should be considered because their gear is voice for these components. This same dealer has Audio Note parts lying around that are probably worth a small fortune. Many years ago, I asked about some caps on a shelf and was informed that they were silver foil Audio Note caps that cost north of $1,000 each.