I compare High Yield to General a lot on undug targets. Often the case is if I've found something in HY, General will usually also see it, but the response may be weaker. But when using General, if I've detected something bigger or more solid, when switching to HY I often get a very wobbly or fluffy response, so General definitely better. So if you want to get all the smaller stuff, stick to HY, but if you don't care about missing the odd tiddler, but like the idea of hitting a better deeper bit, then stick to General.
What is interesting in the graph is that with the 19 in HY and Difficult, seems to be matching the 14 in HY and Normal. I found a lot of my early Zed gold in HY/Norm but was restricted to milder ground. If I can get that level of performance in hotter ground.......fun times