If you sell your S1 now, you will get about 0.20BTc for it.
If you keep it till september 20th it will earn 0.20 BTc (from now) less a contribution for electricity.

by 20th september your S1 will be worthless.

nothing to gain and nothing to loose


Bitmain will not be selling anything else before then.


Then you upgrade it for 0.46Btc (it will then be the equivelent of an S3+)

or buy a new S3+ for 0.58 BTc

Make your choice.