I'm assuming it won't brick or mess up the eDGe, as developers like robot and jcase seem to imply it's a common and harmless type of patch

Personally, I'm of the age where I go with what's "official" and "safe", and if Google hasn't made the Market accessible, then I'm prepared to do without until they make it available. I'm actually doing just fine in finding free apps through third party markets. I don't know exactly how the patch works, and whether it touches core system files that perhaps enTourage have themselves customized.