10.11 Item Types properties are different

So I found that a lot of the 10.10 expressions don't work in 10.11.  for example:

10.10:

LookUp.GetEntry("PayItems","Item", this.Pay_Item).Unit

10.11:

LookUp.GetEntry("PayItems","DESCRIPTION", this["Description"])["BIDITEM"]

same expression, different formatting.  That being said, what is the new method of getting sloped and planar areas?  In 10.10 it was:

System.Math.Round(this.GetElement().MeshSurfaceEntity_PlanarArea)

but that doesn't work in 10.11.

The Help is absolutely no help.  

Thanks in advance,

Mike