I know I'm late to the party but I do want to address this. Trying to figure out if one "cycles" faster or slower is a completely wrong mindset. We use the term cycling because of the term "nitrogen cycle", it has nothing to do with something being started and then complete. It is an ongoing process. The rock maturing and reaching a chemical equilibrium is an ongoing process. Even the "ugly phase" is actually an ongoing process that we can repeat without taking precautions.
All other factors being equal, a nano will be ready for a pair of clownfish at the same time as a 180g system (unless you are relying on dilution from the 180g system to keep your fish safe).