After upgrading Ladybug from v1.0.8 to v1.0.11 the parameters of a \DateTime() object are not dumped anymore. Reverting composer.lock to the Ladybug version from "2013-10-15 09:36:24" does show the parameters ( date, timezone_type, timezone) again.
Gist of the composer.lock can be found here https://gist.github.com/Rvanlaak/d0c4c24cd8ad18e4b2bd