I appreciate the Sutherland recommendations. KC would allow switching among all cartridges, but the TZ is specific to low output MC. KCs seem readily available. Lounge seems to have op-amps, and I might prefer discrete.
theflattire, I have an MP7 in a different system, as an MM only phono pre. I know that there are newer models without an SUT requirement for MC cartridges. I'd recommend it as well, and I'm using it with a 2M Black. It's a keeper.
inagroove, the Zesto does seem to be pretty adjustable. A nice one sold recently. I appreciate that the 103Rs may have led you there.
armstrod, I do like the ability to roll 12AX7s. I have multiple pairs and some familiarity as a result. The Aric Audio Unlimited II uses them as well.
danmar123, that piece is a work of art. I don't know anything about it. I'm going off to read some reviews on these suggestions.
I've used a Parks Puffin, and enjoyed the adjustability and tweak potential. I wonder about picking one up again, used. I replaced it with the Darlington, which has been a keeper.
Thanks to all for the recommendations so far. What appeals to me about this particular cartridge is the product lifetime, and the fact that there's an aftermarket if you'd like to go further, rather than add another cartridge to the collection.