I've just made two buttons up on my shelf.

One for converting the selected poly object to subds.
The other for converting a subd model to polys.

Rather than do through the same trauma with the do and undo method, I just convert then convert back.

The script behind the two buttons I use is:

Polys -> Subds
doSubdivCreate( "2", { "1","1","2000","32"} )

SubDs -> polys
TesselateSubdivSurface

I just ctrl-shift then selected the option from the menu. This way you get the icon and status-bar text set for each button. It also means that convert buttons will keep the current options for each tool.

Just make sure you set the Tesselation Method to vertices, and Original Object to replace for the subd -> poly conversion.

The poly->subd conversion should have the Keep Original checkbox unchecked.

Failing that, if you know your way around the hypergraph, you can show all nodes of an object then just delete the part of the model that didn't get uncreated when you hit undo.


Should keep you out of troube guys.
Simon