I moved from a 3B ST to a 3B SST and completely agree with rob80b's description of the positive changes. From my reading there is less of a change form SST to SST2.
BUT- there are rarely night and day changes in audio. High end audio is all about relatively minor and subtle changes ( especially with anything other than loudspeakers) . Each audiophile has to decide how meaningful, ( and they can be very meaningful ) each of these often very expensive changes means to their own musical enjoyment.