Harrison Consoles are selling the full MixBus Essentials pack for a lower price and including the XT Equaliser for free. I bought into it and have basically got all the plugins now including the mastering plugins.
I can say the Reverb is very nice and so is the delay very interesting. The XT Equaliser is also very good and a scaled down version of the mastering EQ. They both have a very nice way of drawing EQ curves.
Between all the built in stuff in the channel strips/buses/masterbuss eg dynamics and EQ's and the extra plugins you have got a lot of bases covered. There is not much more you need. It means you can complete a mix and do more processing inside Mixbus and less processing before exporting stems and tracks from your DAW after all your editing and just prior to doing your mix.