Don't get too hung up on percentages of DNA exactly. The important difference is in the soul, which then manifests into the DNA. Someone who has Yehuborim DNA has a Yehuborim soul by definition and this is still very small relative to the whole Gentile population. It is not like you would just randomly acquire Yehuborim DNA by some accident 300 years ago, but rather you would have been descended from a Yehuborim parent and soul.
The enemy is parasitic by nature and therefore will intentionally mix into populations in order to make it harder to distinguish. This doesn't mean it doesn't exist on a soul level, though.
So in regards to trusting them based on the reason that they may relinquish their attacks on Satan, this is not likely because they are connected based on thousands of years of anti-Satanic practice by the Rabbis and associated negative entities. It is a matter of probability here, similar to the story of not trusting a snake after it has just bit you.
If the Yehubor was to change themselves, this would likely require hundreds of years of work which they are not likely to ever perform, and likely cannot even do, like if our energy and practices are hostile towards them, just as their practices create insanity in us.
I believe their story is one of negative karma and negative behavior being compiled for thousands of years, as HPHC has described in a previous sermon on their past. It isn't something that can be undone by just 5 years of meditation. That is why people here are giving you conservative stances, rather than expressing optimism.