differences between tube and solid state designs

this topic may have been beaten to death.

however, my experience attending ces shows has demonstrated to my eras that the differences between push pull tube and solid state amplifiers sound very similar.

i notice today's tube amps, e.g., contad johnson, audio research, wolcott audio, etc., do not exhibit many of the classic colorations associated with tube designs and sound a lot like solid state, especially with respect to frequency response, i.e., spectral balance.

there may be still be slight audible differences between the 2 formats.

has anyone perceived a narrowing of sonic differences between the two designs and if so if differences are slight, why buy a tube amp.

note, i have deliberately excluded class a and single ended amps, at low wattage, from this discussion. some of them have more of a vintage or classic tube sound, especially relative to bass and treble response.