well, you can hack it. This doesn’t work by percent of poly, but rather absolute distance, so either your mesh should have fairly equally sized polys (or the smaller ones will dissappear or be inverted).
First make a copy of your object in a new layer. Press ctrl-U to unweld points. If the polys are roughly square and 25 mm2 (5x5) then replicate the polys by 2,5 mm, flip them, press ctrl c to copy them. Flip them again and bevel them 5 mm. Give everything a new material/surface name, e.g. TEMP_SURFACE and paste the originals back and merge points. You now have alot of 125 mm3 (5x5x5) cubes instead of single polys. Now you can replicate these up or down to the size you want them. And when you’re done select by surface TEMP_SURFACE, delete the polygons that are selected and you’re left with the scaled original ones. Now just replicate them back onto the original object (which you can have in a background layer for reference.
OMG… I just realized that all you need to do is select all polys, bevel them to the size you want (using inset, not shift), copy selected polys, delete all and finally paste back.
DOH lol
Still works only in absolute distance, though.