What are the most balanced relatively neutral cartridges at each price level ?

You don't compare vinyl to digital, you compare it to master tape dubs

Not me, mate.  I know what a full orchestra sounds like in a good acoustic.  That's what I use as a reference.

For level 4, the answer WAS Tranfiguration, now sadly defunct.  The most tonally neutral LOMCs I ever heard. At level 1, Nagaoka MP500 is as good a choice as any other.

So do I know how orchestra sounds, and small bands, and vocals etc.

Unfortunately, some tape masters deteriorated and their dubs will no longer be reference, in this case your original pressing record will be reference. And if you can find a successful test pressing..

I have little problem with audiophile "sound engineering", by the way, for as long as the essence of the performance is conveyed, but personally I would prefer doing it down the chain not at the source. On the other hand, many esteemed audiophiles use Koetsu and Lyra, so perhaps they are right to start doing it at the source. Still, I am a tape man and my philosophy is sometimes a little different. Difficult to bring out the full colour and vividness of the performance without adding some  colourations, doesn't it ? Koetsu cartridges, better Mullard tubes, some cables..

Perhaps, the different "flavors" one finds from cartridges explains why some people have a large collection of cartridges; some people don't just want vanilla and they like to mix things up.  The cartridges I like don't at all sound alike.  I like the Koetsu Rosewood Platinum Signature and the Audio Technica AT ART1000, both heard in the same system.  I like my Lyra Titan and my Transfiguration Orpheus L even though they don't sound alike.  I've heard, and liked other Lyra cartridges, certain Dynavector and Allaerte cartridges.  For reasons I can't explain, I did not warm up to ZYX cartridges.  I once kidded a friend when I recommended that he get a Van Den Hul Colibri cartridge--it is a very fast and lively sounding cartridge which is exciting to hear, but, I probably would not want to live with it--which is why I wanted someone else to get it so I could play with it.