These motor/generators are rated at 200A continuous.  The Kv is 41rpm/V.  

You can certainly buy higher voltage controllers.  In terms of the overall system cost it is not that significant to go for a higher voltage but you would need to check that its adjustments allow for the conditions you might encounter.  You may also need to read the fine print though because it may have problems handling a runaway condition.  The first controllers used on the 18m proa were not capable of reversing if the prop was still turning.  The supplier suggested we should drop the anchor and come to a stop by that means then select the new direction and lift the anchor; not a practical option approaching a marina with a tail wind.  The controllers we found that could reverse with props still spinning have a maximum rating of 60V.  

You can bet you will be at the bleeding edge trying to regenerate on a fast, lightweight sailing boat using the propulsion system.  If you can only motor in one direction then you have cut the possible usage to 50%.  You will not want to use when going to weather.  That is also 50% of the time so now down to 25%.  You will not use it if sailing below 6kts on any point because it will kill speed just being in the water.  You will not want to use it in conditions above 15kts of wind because the sea conditions will be demanding and you will not want to have the complication of a tender in the water.  So there could be a useful window for regeneration around 5 to 10% of your sailing time.  The limited opportunity to get something out of it means that you should not be relying on it.  

Rick