I have a full Bottllehead system, consisting of a BeePre 2 preamp, a Kaiju 8W power amp, a Mainline headphone amp, and an Eros 2 phono preamp. The BeePre and Kaiju use 300B tubes. I am running Bottlehead Jager speakers, which are 94 dB, and are voiced to work well with low-power SET setups. This is my main system, and I love how it sounds. I haven't done much in the way of modifying my kits from OEM, but lots of people upgrade their Bottlehead gear with boutique components. My secondary system consists of a Rega Elex Mk4, 72W integrated amp with Dynaudio Contour 20 speakers and a subwoofer. I find that I like the Bottlehead system at least as much as my SS system. It won't totally rock a large room at only 8W, but in my smaller space the Bottlehead SET system is very sweet and engaging.
Bottlehead kits come with awesome instructions, and their excellent forum provides the extra help one sometimes needs when assembling the kits. If you can solder and are at least a bit mechanically inclined, Bottlehead kits are a lot of fun to put together. I highly recommend them.