Privet is child's play, wait until you start removing Tallow trees, their root system is way more extensive. Both are invasive and gifts from Asia. Also, Formosa trees need to be kept at bay.
You’re right the little B26 works great on shallow rooted bushes and small trees. So maneuverable with great lines of sight and control. On the bigger M59 a real tree terror. Few stabs with the excavator teeth, root saw/cutter splines on top then bigger trees just faint over. All well controlled.
New ones have option of cutter teeth on the sides too. If working big stuff all the time probably a good feature. Surprised how fast those teeth can cut. For me often reaching near mature trees I want to keep and near fence lines the saws on top and smooth sides works best.