RH84 uses plate to grid local feeedback around the EL-84, as does Seductor. But Seductor is direct coupled and uses a pentode driver instead of a triode, which gives it quite a different character. It was clean-sounding, but I didn't think it had much of the Bottlehead sound - or the special character of the EL-84. Since then, I've learned more about these circuits, and I would do it differently today. (I'll continue to study these circuit ideas, since they do have some advantages.)
Quite a number of people have built the RH-84 and other RH amps, whereas only a few Seductors were ever sold. So you'd probably be better off to do the RH and check the DIYaudio and/or other forums for experience and help.
