That's actually a great question. 
I have not noticed an issue with accuracy of plot points on my 665.
However (dealing with accuracy in general) I'll expand the question a bit. More-so an additional ask of the same question worded a bit differently ... yeah?
Does anyone know if Garmin is keeping up with "Roadtech" version of their units for H-D dealers that have closed?
If they are not - meaning there are H-D dealers listed that don't exist - then the value of the "Roadtech" series goes down a notch in my book.
Isn't that (aside from NIM functionality - because that was an add-on) why H-D did the "Roadtech" version in the first place?
You are right there, TiF
2! The premium price for the HD one over the Garmin one was supposedly in part because it contained the location of dealers, but - although it reports as V3.0 - I'm not aware of any updates ever having appeared. And I've chased dealerships all over cities in Europe (Tallin in Estonia, Thessaloniki in Greece) by choosing them as a destination in the 660, only to discover the supposed location is miles away from the dealership, and that's NOT because the dealership has moved! The details HD give sometimes include the correct address, but that's nowhere near the coordinates in the GPS. See the example below (Thessaloniki in Greece) for what I mean, where the address for the entry is correct, but the location nowhere near. And these "errors" (as an aside, the old GPS built into the HK head unit was every bit as bad in this respect, and it was never updated) seem to be the rule, not the exception.
As seems to be the norm these days, the MoCo subject us to "Mushroom Management", and have some junior who is either too stupid to know how, or too lazy to care, stick pins in a city rather than get the correct location. To get this correct for the whole of Europe would take less than a day for someone with the IQ of a plant, but HD couldn't care less - they've got our money, and how they must laugh at us for being mugs!

Jim