Having 134 vintage cartridges and having bought/tried/sold 5 MC carts, there are points not mentioned, and poorly explained in this thread.
MC carts do NOT have the edge in detail or lower moving mass. And while MM and MI carts work identically, there are some major differences; these are not explained in this thread.
I’ve had 2 Dynavectors, an AT and an Ortofon MC. If your previous MM/MI carts were average, then MC wins. But I have more than several really good MI carts, and 2 Micro Acoustics carts that trounce the MCs. And….Low compliance MCs ruin any mass advantage they might have. They are low compliance because the MC designers can’t overcome the coil wire problems with high compliance suspensions. Rob Peter to pay Paul. Make a stiff suspension to hide the coil wire compliance issues.
Micro Acoustics cartridges give you the best of all worlds; high compliance, very low mass, immunity from loading, very high detail/texture, and flat FR.
MI is a subset of MM. But there is a major difference no one talks about, because most don’t know how MM and MI work. Problem with an MM is that the magnet has a N and a S pole; the magnet has to be long enough to ONLY present 1 magnet pole to the coil poles. A short magnet will present both N and S poles in the coil pole gap, causing distortion from simultaneous - and + voltage swings. This makes for a heavy mass on the cantilever even when using rare earth magnets.
MI cartridges are different from MM in one very important aspect: Mono-pole magnet. Only ONE magnet pole (N or S) is induced into the hollow and very light iron armature. So the vibrating armature in the coil pole gap only has a single magnetic charge. The armature is very effectively an extension of only 1pole of the permanent magnet. This produces a pure music sine wave in the coils; it’s that clean and effortless sound well-made MI carts are known for.
I have several MI carts, and the Micro Acoustics carts that leave the $5,000 Dynavector carts wanting. And the AT and Ortofon MC carts.