All the 3D models I sculpt are only for 3d-printing (without color). All fine details are therefore lost in the printing (and would have to be sanded down if they survive anyway). I use Optimize instead of Decimation Master. I find no need for other brushes than the one I already have. I never need more than 20 million polygons. Is there any reason for upgrading?
Only you can decide whether ZBrushCore is enough for your needs. If you feel it meets all your requirements then there’s no need to upgrade to the full version. But anyway, if you want to try out ZBrush you can always get the trial version which gives you 45 days to really find out if it’s for you!