Back to the loading question: is the proper loading more a function of the phono pre or the cartridge itself?Ayre made their recommendation to you on account of the fact that they did the proper homework in their design of their phono section.
There is another thread active on this forum that relates to this topic. So I am repeating myself here: The loading resistor is primarily for the benefit of the phono section, not the cartridge (although decreasing the load resistor value will decrease the compliance of the cantilever). The cartridge has an inductance and the tone arm cable (and to a certain extent, also the input of the phono section) has a capacitance. They are in parallel. Anytime you find an inductance and a capacitance in parallel you have a tuned circuit, also known as a 'tank circuit' (as it stores AC energy) which resonates at a certain frequency. BTW an inductance in parallel with a capacitance is the means used to tune a radio to a station.
Since the inductance of a moving coil is usually slight and capacitance of the cable is also low (or should be) the resonant frequency is rather high and can be anywhere from several 100KHz to several MHz. This resonance is a peak and can be as much as 30dB! When the peak is at resonance, the term for this is 'excitation'. The energy of the cartridge itself is enough to drive the tank circuit into excitation.
Essentially as far as the phono preamp is concerned this energy is RFI (Radio Frequency Interference) and is injected directly into the input of the phono section! It can overload the input of the phono section and this can result in a tick or a pop. So to avoid this problem the input of the phono section should be designed with plenty of headroom.
The loading resistor suggested is in parallel with the tank circuit. It acts to detune the tank circuit and prevent resonance. Since a cartridge manufacturer has no idea of how competent the phono section to which the cartridge is connected will be, they often recommend a low loading value to allow that phono section to operate correctly. Its well-known that RFI causes audio electronics to not sound right (often brighter)!
But if the phono section is RFI immune and has good overload margins, the loading resistor simply isn't needed. This allows the cartridge greater compliance and can result in better tracking performance, depending to some extent on the tone arm. Right about here things get a bit complex, but as a general rule of thumb most cartridges are designed to drive 47Kohms, despite the 100 ohm loading recommendation.
The bottom line is try it both ways and see.