We'd love to have the effort as a rankable property rather than any pre-defined factor.
It's easy to say
"A is harder than B, but easier than C"
. It's a lot harder to give an effort value.
A trite example. I have a few features:
  • A is effort 2
  • B is effort 3
  • C is effort 4
  • D is effort 5
  • E is effort 5
I need to add
Feature X
, which is harder than C, but easier than D and E. I now have to adjust the efforts of all adjacent features in one direction:
  • A is effort
    1
  • B is effort
    2
  • C is effort
    3
  • X is effort 4
  • D is effort 5
  • E is effort 5
Realistically, I'd rather drag the new feature into place and forget all about numbers.