Thanks for asking, good question.
Pay Mode is one of the cool features of SafeZone, and really the original idea behind SafeZone if you ask me. It provides a pretty bullet-proof insulation of everything that's happening in the Pay Mode tab, both from local eavesdroppers (e.g. keyloggers, screen-scrapers etc) as well as network-level eavesdroppers (DNS hijackers etc).
But, SafeZone comes with top security features even outside of the Pay Mode tabs. The security and anti-phishing plugin is baked in (instead of being supplied by means of a browser extension), and supports for inspection of all traffic (including encrypted / HTTPS traffic etc).
The general motivation behind SafeZone is the following: all browsers in general make it increasingly more difficult for security software to interact with them. Low-level extensions, Javascript scanning, HTTPS scanning, shielding of individual sessions -- all of this is becoming pretty much impossible to do in a 3rd party browser, as the browser landscape evolves. You can clearly see the trend -- which is, for the most part, dictated by Chrome, but the other major browser vendors follow the suit.
Now, to give people more reasons to try and use SafeZone, we have added a couple of more mainstream features into it as well, such as ad-blocking and the ability to save streaming videos. Of course, these are not security features per se, but they make the browser run snappier and provide more convenience. Our ultimate goal is to make SafeZone as comfortable to use (if not more) than the current browser you are using today, and keep adding more security features on top of it as we go. That's because we realize that in the long run, it will be more and more difficult to provide added security to 3rd party browsers, at least in an official / documented fashion.
Hope this helps,
Vlk