I won't go back to B4 at all. Love B5. Hope you have a honcho CPU and if you don't, then keep the render options low and it works just like B4. Only real addition is treelab. The lighting lab merely collected the lighting controls in one place. Some user improvements in the terrain/lattice editor, but no additional tools there. Matlab is the same. I hardly do metaballs in B5, though I've seen some great work. Reason is the metaballs in Metasequoia still are far superior. But its a start. Doubt B6 will be out any time soon, and even if it does come out in the next half year, the learning curve in B5 will be worth it. Best wishes to you. B5 is not a huge improvement, but a good one none the less.