Hi, I have the motif xs rack and the motif xf 8. The soundbanks are either identical or splitting hairs similar. The improvements are laid out pretty clear on the Yamaha motif site, worth a look when deciding. I love my motif xf, but having only used the xs rack prior I couldnt say whether the upgrade from an xs workstation to a xf workstation is worth it.
Micron, Motif XF8, Reaper