Is there any written docs regarding which tools are planned in the subD toolset?
A few of essentials for me are ‘Loop Select’, ‘Loop Slice’, ‘Bridge’, ‘Edge extend’, ‘Thicken’.
Hi,
There’s the Rhino SubD Status document that you can find here:
It would be good, though, to give clear and concise examples of the functionality that you find necessary. Only providing the names of concepts that exist in other software might not always be interpreted correctly by the intended receiver…
Many if the mentioned operations you mention are worked on for meshes at least - I assume it shouldn’t be a big jump to see them for subd usage.
I have some polygon subd-modelling experience (Blender), I try to give my opinion on the tools whereever I can (:
I don’t have a lot of experience with subD modeling…just some basic tools for day to day work which cover my needs. Nathan probably has more workable knowledge.
A Slice tool and a Bridge tool would be great! 
Is Slice similar to Loop Cut?
Similar in that you are cutting but it’s a slice across a face or faces along the direction of the moved mouse. Or slice with curve …same as in nurbs toolset.
That sounds like Blenders Knife Cut
Sounds right.