There are many reason for this
If you have Sobi2 and need to move to Joomla 2.5 this is your only option , because You can not go from Sobi2 to SobiPro, Sobi did not offer an upgrade package.
Mosets support is great. They supported me through the whole migration process from SOBI2 to MosetsTree. All my request was answered at the shortest possible time. My directory with 150 000 entries works perfectly.
Thank you, for great component.