Here is a trial done with various types of sealant and tubes.
Tire Sealants - Slowtwitch.com
Sealant Test - Part 1 - Slowtwitch.com
Sealant Test - Part 2 - Slowtwitch.com
One can't necessarily compare it to tubeless, but the Orange sealant was rated highly.
One is supposed to periodically renew the sealant. Did you do that?
It is also possible the period or reduced pressure helped the tube seal independent of the sealant used.
Nonetheless, it sounds like your adding Stans gave you impressive results.