m.k., indeed... you uncovered yet another facet of this valuation that DR hasn't forecast yet, because both mako and proteus are too new to be in the numbers yet.
personally, i think they'll rent just as many protei as they sell, and they will probably be a very high-ticket high-margin item. jmho.
and oh, btw -- how many protei would rent out for extended contracts during a heavy hurricane season with some major damage out there in the gulf... or even globally, for that matter?
for all we know mako will turn DPDW into a world-wide hurricane/cyclone/typhoon play. proteus seems like it would be integral to undersea construction/repair work after storm damage.
and... this is a big planet with plenty of heavy weather.