Double checking, the "at least double" and "slightly higher capacity factor" might be considered inaccurate.
Onshore vs offshore wind energy: types of wind energy, difference and cost
This site suggests a 43% price increase per MW, but capacity factor goes to 38% from 24%, a 58% increase.
So if we take $3.13M per MW divided by .24 = $13M per capacity factor adjusted continuous MW for onshore.
$4.49M per MW for offshore divided by .38 = $12M per MW adjusted.
Though NREL 2024 has levelized cost of energy for offshore fixed bottom wind turbines being almost 3 times the price as land based.
IRENA has on-shore at around $0.042 per kWh, and offshore around 0.062, around 50% more.
My thinking is thus that a mix of both might be good, as the more install areas we have, the more level the production is likely to be, reducing the need for storage. Plus, would depend on whether or not the power provider has good on-land areas for wind turbines, or good offshore areas. Texas has a lot of good spots on land, while states like New York, or the east coast in general, may not.