S1-your own power supply.
S2-same chips as S1, big case, power supply.
S3-your own power supply.
S3+-same chips as S3, but overclocked.
S4-same chips as S3, big case, power supply.
S4+-same chips as S3, more chips than S4.
S5-your own power supply.
S5+-your own power supply, over three times more chips than S5.
S6-no big case with power supply using the same chips as S5.
S7-the newest chips.
Feel to me like they finished up the chips they had with the S5+ which fill the niche of what the S6 would be if they kept the tick tock rate.
Hence why i find it very possible the S6 or maybe S8 if they skip the S6 altogether, whatever next even # form factor they come up with, will be with BM1385.