My thoughts is that if you plan to pole small groups (3-4) of green mobs, light can also be an option. The +6 evasion and the lower attack power of mobs can compensate for the less Pdef. My dwarf poled alone easily in NoS with salamander.
Unless of course you have a DEX tat and an EE in party. Then Light can be effective also.
This only works, however, if you get light armor masteries, ie. warlord, warsmith, destroyer, in addition to your polearm masteries. If you are missing either pole skills or light armor skills, then you will want to use heavy armor.
Also, VR is generally a necessity in Pole parties, although it can be avoided if your puller pulls properly and you have a good healer.