I have both and there's a lot of difference, actually. It has half the gain of the 77CA and the difference is very noticeable in both the 150 Mhz and 450 Mhz range. While the 77CA is not tuned for low band, it will do a decent job if you have any low band frequencies in your area. The 707 is completely deaf in the low band. I bought the 707 because of the hinged base so I could have the antenna vertical on my VX-2R when it was on the desk or on my car seat. It's a great antenna for 2 meters and 70 centimeters but doesn't do well outside of that range at all. Even though the 77CA is more unwieldy because of its length, it's a much better antenna for a scanner.
