SV4000 is slightly better - here's why. 1. SV4000 is slightly cheaper than Ultra. 2. With less frequent BIN changes, I have had not problems with reception.
Vs,just has more constant improvments,I haven't changed my bin since ....[can't remember when].I haven't reflashed because it isn't required,but nice to know team VS is ALWAYS making inprovents.Soniview maybe related ,but gets its help from team VS.