I decided to pick up a V4 6-24x50 and do a full comparison to my HD5 5-25x50. I wanted to make sure I wasn't sacrificing on glass quality by making the switch. I'll try not to duplicate points noted in Tim King's review. I did the comparison at dusk on 24 power.
Glass: I set both scopes looking into a shadowed area under some trees at 300 yards. Weather was clear. Clarity was basically the same across the field of view. The color seemed to be a bit more true in the HD5. The parallax adjustments seemed to be easier to achieve with the HD5. The direction of rotation of the parallax knobs are reversed between the two models. Scopes started to see a diminish in lighting exactly at dusk. 10 minutes after, they seemed to loose a bit more light but had more than enough to see clearly. I stopped the test 15 min after dusk. I think it would be safe to say that on a cloudy day, you could easily see until dusk at 24 power. Both scopes were equal in this respect. Overall, I would score the HD5 glass a 9.5/10 and the V4 an 9.4/10.
Turrets: The HD5 turrets have a positive click feel and sound. The V4 feels and sounds much softer in comparison. There is no slop or over travel in setting its position. Windage knob is ultra basic. Small with tightly spaced hash marks marked on one half of the knob. Clicks are more audible than the elevation knob. The windage knob has the quick reset-to-zero feature by pulling out and twisting. With the MOA1 reticle, I don't plan on dialing for wind much.
Overall, I would give a very slight edge to the HD5 as far as comfort and performance. Even though the V4 is 1" longer, it is noticeably lighter. The main selling points to the V4, as I see them, are the larger adjustment ranges, MOA style reticle, multi turn zero stop, and weight. Some sacrifices were made such as not having a full sized windage turret, lose of the 5x zoom, and glass that may not be quite as good.
