MM cart loading vs HF response

I feel like I should know this, but I guess not. For a moving magnet cartridge, will increasing the capacitive loading it sees boost or cut its high frequency response? Is there a fixed turnover knee frequency and dB/octave that's purely a function of the capacitive loading regardless of MM cart & preamp?

My cart wants to see 400pF. It sees 80pF cable loading (tonearm + phono cable) and 220pF phono preamp loading = 300pF. This cart has a removable sandwich cap that fits behind the body touching all four pins, adding another 200pF = 500pF. I can't hear a huge difference either way, but it takes 15min to insert the cap and rebalance the tonearm so it's not a straight A/B.

Going by the book then, which loading will reduce high frequency output? In an effort to reduce HFs with a Whest and Thiels, how far can I stray from the recommended 400pF to achieve a noticeable HF reduction by altering the Whest's loading caps? With what undesirable sonic side-effects from going too far from Ortofon's recommendation?
OK then, I'll simplify my question:

Does adding load capacitance to a MM cartridge increase or decrease its high-frequency output?

Any MM owner with a decent phono stage that offers easily-selectable capacitive loading can answer that, unless the entire audiophile community has gone to MCs.
Take a look here:

I Hope this help.