What settings do people use with Lyra cartridges?

The 100 ohm value suggests that your preamp is unhappy with RFI (Radio Frequency Interference) at its input.

The 100 ohm value detunes the RF circuit caused by the tone arm interconnect cable and the inductance of the cartridge. As a consequence, the optimal loading value varies from cable to cable. Of course, if your preamp is stable with RFI at its input, the loading value will cease to be a concern. 

If your preamp has stability problems, start with 100 ohms.

If your preamp does not have stability problems, you will be fine with the stock 47K. Loading has everything to do with the preamp and not so much to do with the cartridge when it come to low output moving coil cartridges.

The loading is killing a high frequency resonance that is ultra-sonic or ever Radio Frequency (RF) in nature. If your preamp does not care about that energy being injected into its input, the loading will have no effect. If you preamp doesn't like that energy, you will hear the effects of the loading right away.

If you ask J Carr about loading, you will find that he says the same thing that I do.

What is happening is the cartridge inductance interacts with the tone  arm cable capacitance to form a tuned Radio Frequency (RF) circuit. It resonates when energized by the cartridge itself. This causes ultrasonic or RF energy to be injected into the input of the preamp.

If the preamp is stable with such energy you will hear no effect from loading. If the preamp is unstable and reacts poorly to such energy, the loading resistor is then used to detune the tank circuit (another way of saying 'resonant circuit') and thus it sounds better with the loading.

I have tested many LOMC cartridges- when you 'ring' them with a squarewave and then test to see what a loading resistor does to the squarewave, you see that it has absolutely no effect whatsoever at audio frequencies. Its all happening at much higher frequencies.

IOW, if loading sounds better it means the phono preamp is unstable. You might want to read this thread in which J Carr is quite active:
http://www.whatsbestforum.com/showthread.php?15077-Cartridge-Loading-A-Misnomer

I met up with Jonathan at the Munich show last year and we had a conversation about this- and touched on the fact that loading the cartridge might well have a negative effect on its ability to track. He touches on this in the opening post of thread at the link.