Studied some of this wave propagation stuff when I was getting ready to take the FCC exam to become WB7QDL. Have since talked with engineers that were involved with early broadcast efforts and have done some of my own using of most of the frequencies we're talking about.

As mentioned, the 700 MHz is close enough to what is generally referred to as microwave, that a significant portion of it's energy is expended, trying to heat the water in the leaves of any trees that it might need to pass through, to get from point A to point B. 450 MHz doesn't try to heat water as much, so it can go through leaves better. In a congested urban canyon of tall reflective buildings, 450 has more of a tendency to bounce off buildings and ricochet to get to where it is desired, than longer wavelengths like 150 MHz. Not going to be enough bending to get any kind of ground wave though.

To get into the realm of enough bending to have a significant ground wave, you're going to need to get down around .5 MHz or 600 Meters wavelength. A quarter wave antenna, at that freq. is going to be about 500 feet high!