Could you give a more concrete use-case for it?

Right now you can keep it to the forums. I'll see if I can arrange a proper node tree sharing page :)

Although if you are really eager to share somewhere, I suppose you could see if you can get people to start a Unity wiki page on it

Possibly, although the Texture2D node is large and cluttered already as it is. Not sure how to smoothly fit that functionality in there, unless it's somewhat hidden

This has now been fixed in Beta 0.26

Strange, this should have happened tonnes of times before now that I looked at the code for it, scary!

This has now been fixed in 0.26

That's because it's (incorrectly) outputting a 4-component output when you have a 4-component as a mask. As a temporary solution - add a component mask afterwards, masking out RGB