I have Comet non-ghosting LEDs in my inserts in most of my games and I do not see any ghosting or flickering. No LED OCD board in any of my games.

Non-ghosting LEDs will prevent flickering in the case where a bulb is supposed to be unlit, but you'll see subtle flickering. This is because there is a small amount of voltage at the socket that wasn't enough to illuminate an incandescent bulb...but it's enough to illuminate an LED.

LED OCD boards are primarily designed to deal with fading effects. These fading effects which were originally designed for incandescents just don't look as smooth with LEDs. Example: the LOTR Fellowship inserts pulse in and out during gameplay. Installing LEDs makes this effect choppy, but the LED OCD will fix it.

Unless I'm missing something, most WPC games do not use fading effects on inserts during gameplay...however it's likely that attract mode will be smoothed out with LED OCD.

I've never used LED OCD for GI...but it's unnecessary in most games because the GI is either fully on, or fully off (ie: no fading effects). Does Dirty Harry have GI fading effects? A few games I can think of that have noticeable effects are Addams Family and Theater of Magic. Many WPC games also have an option in the settings to turn off GI dimming.

TL;DR Non-ghosting bulbs will likely fix most of your issues. I would try those before going full LED OCD. (If you buy non-ghosting bulbs from Comet, and decide that it isn't enough and you want LED OCD, you can return the bulbs and we'll refund you (because for the LED OCD boards it's better to have standard LEDs, rather than non-ghosting)).

Another nice feature of OCD LED is the ability to individually control the brightness of each individual bulb separately. I find this particularly useful if you have OCD like myself (pun intended) and you want the visual feel of your blue bulbs to match your orange bulbs and your red bulbs. Meaning that to me on a stock setting even bulbs of the same design but of different color have different “brightness levels” to my eye without the OCD LED board. Not sure this would be solved with non-ghosting LED’s because the same principle is in effect for the most part. But again, not an issue unless you have OCD (the disorder, not the board).

Be sure to go into the game software adjustments menu and set these two adjustments:

A1. 25 Allow Dim Illumination set to "NO"

A1. 29 General Illumination Power Saver set to "OFF"

I had to turn GI dimming off on my Dirty Harry after installing some GI LEDs. I haven't decided if I want to buy a GI LED OCD board yet. I haven't really noticed that GI dimming is disable. I had to do the same thing on Corvette when I owned it.