I have not yet had occasion to fly with the ARC V.
However, I have had the two side by side, and there is a difference, though it's not overwhelming, at least not head on. Think about it, we're talking about the difference between 4 LEDs and 5 LEDs (I assume they use the same LEDs).
The lenses may be different between the II and the V. If so, off-axis brightness would probably vary, even if the number of LEDs was unchanged.
It goes back to what you have now, and what you want to do:
If you don't have a strobe yet, I absolutely recommend the ARC V. Compared to the ARC II, the ARC V wins in every area.
If you already have a good strobe, like the ARC II, I'd keep it, but buy the ARC V to use --in addition to--- the ARC II - this is what I'm going to do - a white ARC V attached to Mavic Air battery, and pointing down, a white ARC II facing forward, attached to a front arm, and a red one on the other front arm.
When you say "at a distance", I'll assume you mean over 500 ft. Distance matters, as does height. If you have a downward facing strobe, it's going to be brightest when the drone is directly overhead, but as you move away, the brightness will drop because you're looking at the strobe from the side. If you're more concerned about visibility at a distance, then you'd want to do a side install or front/back...or do BOTH!