MONO cartridges

I recently purchased a Lyra Helikon mono to play the many mono records in my lp collection. First record after break in
was excellent condition original Blue Note records "Art Blakley and the Jazz Messengers Vol. 2". Stunning presentation and detail even compared to my Airtight PC-l stereo cartridge. Several other Blue Notes produced similar results.
My phono pre is a balanced Einstein "The Turntables Choice".
I tried a Shelter 501 Mk 2 mono which has a single coil, but it's single coil design caused a low volume ground hum which is sometimes the result of using a modern phono pre with a single coil mono cartridge. Since the hum was pretty low, I was still able to ascertain that the Lyra presentation was clearer,larger,and more detailed and alive than the Shelter. Of course it's double the price too.
Got the same hum with my Einstein single ended phono pre
and my AHT Non-Signature phono pre [same design as the Walker phono pre without all the added tweaks,etc]
Be careful if you opt for a single coil pickup at the lower price point that it does not hum with your phono pre.

I have a question as to the best loading for the Helikon.
It's specs say 100ohms to 47k ohms. My Einstein has loading resisters of 40,85,100,150,300, and 940 ohms.
Is this cartridge load sensitive in anyone's experience?
What loading are the other owners using and the results?
None of the reviews of this cartridge comment on loading differences. The instructions talk about the potential difference, but I cannot clearly hear one in a quick initial comparison, but I didin't try very hard. Just wanted to sit and listen to the beautiful music I was finally hearing from those records. Waited a long time for this moment, so testing will have to wait. Thanks for any input.
I have mounted it on a Dynavector 507 Mk 2 arm on my TW Accoustic Raven one TT.

Jonathan, thank you for the additional information. That filled in several "gaps" in the previous information I accumulated.

hevak...i've got just shy of 600 lps in mono, most of which are original. for the most part the opened ones are in near mint condition and unless i'm wrong, all sound great. some of these lps i've actually owned since the mid sixties as well, and have always used a stereo cartridge with no sonic shortcomings.

Sabertouch,
I load mine at 1000 ohms.

Jaybo,
Have you tried a mono cartridge? Your mono's could sound better with a mono cartridge.