Hi,
i just found this and want to share my experiences with capacitance multipliers.
I tend to use them more and more in tube microphone preamplifiers where i want psu to function for a long time. As this is are not true regulators, voltage changes a little bit with input signal, but this is not a problem at all with 100-300V which are normally used to power small signal tubes. Slow start might be advantage here, although i never found need for it. The best part in my opinion is low cost and very little heat. I use 5W zeners to clamp the voltage, bypassed by something like 10u film cap, this goes into base of HV transistor like TIP50. Some people suggest 100u lytics for first filering cap, base and output cap. But i found out i can get away with less than 1mVp-p with 100u filtering cap (LL Epcos for very long life) and cheap 10u polypropylene caps into base and output.
Schematic looks more or less like this:
http://www.electronicsinfoline.com/Projects/Electronics/Audio_Project/Audio_Amplifier/regulated_vacuum_tube_power_supply.shtmlAt 300V and 20mA it gets barely warm, so there is no need for heatsinks and Epcos's datasheet shows very, very long life at this condition. I'm not sure if lytic would corrode in this time rather than dry, 7 years old psu like this (i used 150u, 33u, 33u and 33u lytics instead of lytic and two films) is still going strong.