Hi Sebastien,

"Sebastien Vauban"
<wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org> writes:

> Hello,
>
> I'd like to have a couple of different (column) views in my Org file

How about trying this patch which lets you have another format in column
view?

After applying this patch, try this at the Tasks tree in your example.
 M-: (org-columns "%66ITEM(Task) %6CLOCKSUM(Time) %6Effort(Estim.){:}")
to compare with the result of
 M-: (org-columns)

Best,
IP

(snip)
>
> #+TITLE:     Effort vs Estimate
> #+AUTHOR:    Seb Vauban
>
> * Tasks
>   :PROPERTIES:
>   :ID:       49380c04-9b6e-4298-aff8-d936d9679d8e
>   :COLUMNS:  %6TODO %66ITEM(Task) %6Effort(Estim.){:}
>   :END:
>
> ** TODO A
(snip and end)