Ben Nelson was very kind and let me borrow his
scangauge until I get a replacement. Thus I was able to monitor my coolant temps this morning. I can definitely tell a difference. I was up to 150F a lot sooner than I normally am. It normally takes ~2.9 miles to get up to 150F. This morning (which is just as cold as it has been any other morning) it took roughly 1.5 miles to get up to 150F. This is a vast improvement. I only hesitate to say its amazing since it was the first trip with the grill block that I could actually measure.
I also figured it would be a good idea to monitor my 12V battery since they are known to go bad after ~4 years and its now winter, so capacity will be decreased. I turned on the
scangauge before turning the car on to see that the 12V was at 12.1V! Looks like that is going to need to be replaced. Thankfully, owners of the Prius usually notice a mileage increase after replacing the 12V. So, at least there is something to look forward to.