We present coherence-order- and spin-state-selective (COS3) HSQC pulse sequences for 2(I-1z + I-2z)S- --> I-1(-) I-2(alpha/beta) + I-1(alpha/beta) I-2(-) and S- --> I-1(-) I-2(alpha/beta) + I-1(alpha/beta) I-2(-) transfer in I2S spin systems. The sequences provide the theoretical maximum transfer efficiency and improved effective resolution in the I-spin dimension and allow for heteronuclear gradient echoes without loss in sensitivity. For the antiphase transfer the sensitivity is improved by 41% relative to the previous spin-state-selective alpha&beta-HSQC experiment, while the in-phase sequence is the first of its kind. In the regime of well-separated J doublet lines, the sensitivity enhancement amounts to 100% and 65% relative to previous antiphase and in-phase coherence-order-selective experiments, respectively. ;The new COS3 HSQC experiments and previous methods are compared experimentally using beta-O-methyl maltoside.