I have written several times on this forum that 300b tube preference is amplifier/system influenced(not to mention listener's ears). My SET came with the EH golden grid(decent sounding) and I replaced them with the Shuguang Black Treasure(BT). The BT was much better sounding and I happily used them for well over 2 years, I then bought the Takatsuki direct from Japan and they were/are superior in any way you can compare them.
I later bought the EML XLS and the AVVT 32b SL and these are excellent(slight preference for the EML). The EML XLS was significantly better than the BT(direct comparison). The dry and lifeless quality you describe is the polar opposite of my situation. In my system the EML is very organic,fluid, vivid, harmonically rich and very open and transparent, just a wonderful 300b tube. The EML and Takatsuki are the best I've heard in my SET amplifier. So it doesn't surprise me at all that any of these tubes will be ranked differently based on the particular circumstances and listener taste. I'm looking forward to hearing the Elrog 300b and comparing to my two references. My amplifier has clearly revealed each tube's unique character that I've tried so far(ten 300bs up to this point).I've had some very generous loans of 300bs from fellow audiogon members. It has been a lot of fun trying different tubes. I've had this SET amp for going on 6 years and it's stsying put for many more years to come. I understand why you keep returning to SET amplifiers.