"When the wire mesh stone guards are installed on the car it cuts down on the night time visibility by almost 25%. Is this true?"
In my experience, yes. Maybe not 25%, but 20% or so - It's noticeable right after the change-over, but you get used to it. I would expect the same light reduction from ANY stone guard over the headlight lens - You're blocking off light, after all. I also have H4 replacements and I'm running the higher wattage bulbs. I also run really bright H3 driving lights wired in to high beam - Those puppies light up half the world.
If you're concerned about losing some brilliance (from your lights, not necessarily you), you could opt for even more lumens of light with higher power LED bulbs like these:
https://www.amazon.com/dp/B07T...dExvZ0NsaWNrPXRydWU=
I'm planning on going LED once my current bulbs ever burn out. The Auxito version is the same form factor as an incandescent H4 bulb, so no modifications needed. They look pretty interesting.