Hey Michael - thanks for the quick reply :)
Yep I thought that might be a bit of a reach - not something I need very often but would be really handy on the odd occasion - 100 years ago when I was using Bryce, it had something similar which was great for setting up a scene quickly with place-holders (say, just a cube) and then replacing them with the actual objects for the final render

I'll put it on the wish list! :)