Results confirming the high values of Seebeck coefficient phonon-drag component S-ph in SiC are discussed and the relevant consequences to the thermoelectric figure-of-merit ZT=TS(2)sigma/kappa are studied. The fact that Sph increases at low temperatures as similar toT(-2.4) similarly for low-doped p-6H-SiC, Si and Ge is demonstrated. Materials comparison criterion S(ph)similar tokappa/mum(eff), based on heat conductivity, lattice mobility and carrier effective mass is offered and Sph strength proportions 0.1 : 1: 5: 10 for Ge, Si, SiC and C (diamond) are proposed. Related to that high Tapproximate to500K phonon-drag domination limit is obtained for SiC. It is shown that the proportionality S(ph)similar tokappa, yielding ZTsimilar tokappa; could reverse some concepts accepted in thermoelectric material development. The best-case calculations predict good (>0.1) and excellent (>1) ZT values with steep temperature-dependence similar toT(-3...-4) for low temperatures 50divided by200K if sufficiently high electrical conductivity sigma could be ensured. The last condition may be feasible for n-SiC with relatively shallow donor levels but difficult to achieve in the case of P-SiC with relatively deep acceptor levels.