An example of the downside...
I have two manual Lewmar
54 series winches which can be upgraded to electric
(the 66's are already powered, the old 52's are the old style and can't be upgraded)...
However, there appears to be a complete kit for doing this for 12V but Lewmar
says to do the same thing for 24V you have to buy the individual pieces as they don't have a complete kit.
We shall see how much the cost delta
is, the 12V upgrade kit is about $3200 USD per winch
(I only need to do one side) hopefully the 24V parts
are not a huge amount above that.
On the other side, a friends boat which we installed a 12V 2500 watt SW series inverter
resulted in being "outside the recommended wire run length for any size wire" (it is a high frequency inverter
and thus the DC circuit looks a bit like a transmission
line). In the end I designed up a parallel feed which produced a low inductance connection but the run of about 8-9 feet ended up being 4 red pieces of 4/0 wire and 4 black pieces of 4/0 wire!
Wrestling that through the boat was not the easiest thing in the world.
I am just now starting to see some of the equipment
for even larger vessels being 48V equipment. (Thrusters, Winches, Inverters, etc) which has the advantage of being common with the telecom market but the higher voltage in the marine environment
is a bit of a concern for me...