Man, haven't posted on here in years (still keep up with it, though). This is a bit of a sidebar, but since you brought up the example of the Guyver versus Enzyme fight I would like to take a moment and talk about the original OVA compared to the old dub of the original OVA.
As most of you probably know, US Renditions was the first to dub and bring over the original OVA as a set of six VHS tapes with two episodes on each tape, which Manga then re-released as a set of 12 VHS tapes, eventually compiled on to two DVDs. Whenever they did this, they re-dubbed some of the lines with the most of the same voice actors, greatly improving the clarity of some hard to understand moments. This includes the scene where Sho fights Enzyme.
However, when they did this, they also completely changed the mood and delivery of Genzo's lines. Go back and watch the original fight posted above.
Now, watch this:
The old dub of the original.
Instead of just looking malevolent, Genzo sounds and feels like he absolutely abhors Sho with every fiber of his being. I'm not sure why they decided to redo what was as perfect of a delivery as the old dub was, but when they did they took away a great deal of visceral depth from what should be a scene filled with both absolute enmity and abject horror. To be honest, it sort of ruins it for me, and I'm still scratching my head as to why they decided to make the change.