The plank version in Debian Jessie/Sid is a bit old, it being version 0.6.1-1~experimental1 and the plank project has moved on since then. The current version is 0.7.1 which was released on 23 September 2014, and there's talk of 0.8.0 too.
The url for the packages is http://people.ubuntu.com/~ricotz/packages/plank/ and the packages that I used from that site are -
plank_0.7.1-1~~ricotz1_i386.deb libplank0_0.7.1-1~~ricotz1_i386.deb libplank-dev_0.7.1-1~~ricotz1_i386.deb libplank-common_0.7.1-1~~ricotz1_all.deb libplank0-dbg_0.7.1-1~~ricotz1_i386.deb
This has given me a very stable "plank!"