I don't know how I missed this thread earlier, but as a western-Washington resident, here are my two wet cents worth...
The TV weather forecasts here take up a good 10 minutes of the news, because they have to cover all of the microclimates. For a 25-mile radius from Seattle, they will show spot-temp forecasts that vary by double digits (ie, Seattle, Tukwila, Sea-Tac, Renton, Kent, des Moines, Federal Way, Auburn), but it makes a difference depending on multiple factors and larger systems. Some of them are fairly predicatable as compared to general and/or other local microclimate forecasts. For a non-scientific example from my own observations, if there is a 50% chance of rain in Seattle, there is probably an 80% chance of rain in Lynnwood, 15 miles north. If it is going to be extra windy in the Strait of Juan de Fuca, it may be only breezy in Seattle.
Now, the local TV meteos here do a decent job, and they are courteous enough to stagger their reports during the evening news so they can be compared (and they do differ). The Weather Channel (.com) forecasts by zip-code are usually not even close and cast a wide net over a multi-zip area, and the Wunderground forcasts by zip aren't too bad for the areas I check, even the hourlys. I just can't see how a fixed module in a budget device calling itself "precision" could be reliable at all in this region, so I wouldn't make a purchasing decision (for this region) based on that feature or personally spend any time doing accuracy research on it.