I should add a couple of technical points: The Elrog keeps to the original WE spec inasmuch as it draws a filament current of 1.2A at 5V (as does the Takatsuki). The eml XLS draws about 25% more current than this. Most 300B amps can handle this no problem, but they will run hotter as a result (recall that components such as chokes are sensitive to the square of the current that runs through them -- if the current is 25% higher, the square of the current will be 56% higher). Mine runs noticeably cooler with the Elrogs than with the XLS, adjusted for the same volume levels.
However, it's not the case that the Elrog is a WE clone. The fact that thoriated tungsten is used means the gain and transconductance are quite different from the classical WE. First of all, this means you have to turn the volume up on your amp a bit to generate the same sound pressure, but more than that: the frequency response is also different --- you should expect a different-sounding valve. The tone colours and the bass in particular are markedly different, in a way that's difficult to put into words. In fact some people have suggested it should not be called a 300B at all, even though it is a plug-and-play replacement.
As I see it, the Takatsuki is a finely-crafted 'homage' to the original WE (pre-1980s). It keeps to the WE specs and curves almost exactly. If you're looking for the vintage sound, this is the one to have (apart from a pre-1980s WE itself, of course). If you want to push the envelope of what's possible with modern valve technology married with old-skool German workmanship, then the ER is a great choice.
But I realise from reading over this thread that many (most?) of the contributors here are (North) American, and up to now there has been a limited production allotment of Erlogs to the US market.. most of the first three production runs over the past seven months run has gone into Germany, Spain, Denmark, Holland, and Italy. So I don't want to steal your thunder.. when you get the valves, please draw your own conclusions.
