SoftEther is just a "normal" VPN-Software. This mean, this create a secure connection between a client and server. Not more or less.
If you send unencrypted traffic (like http) through the VPN, the server will (and must) get the unencrypted data. No one can prevent him from copy and save the received data.
If you send encrypted data (https) through the vpn, the server-owner only get the secured https-packages. But of course, he can manipulate it too. To be exachtly, he must. But you can't be sure it's only in the necessary way (change source address to the vpn-server ones) or in the bad-way (change destination address to a other one).
Of course, if all works right, your browser should give you a certification warning, but how often they are ignored?
And maybe, the server-owner redirect one of your normal http-requests to a manipulated site, which use a exploit to install "the hackers" root-certificat-authority? Then the wrong certificate of your https-connection will also be accepted by your browser.
So, a VPN (SoftEther or any other) isn't a safety-profit, if you use it to change your IP. It only change the point, where you go to the internet with the disadvantage, that all traffic goes through a potential unsafe access point.
And specally for vpngate, everybody can "donate" a server. So I would not use vpngate for private things like online banking. Because I trust my ISP more than a unknown server-operator ;)
But If you can trust the server (for examples, you installed SoftEther on your PC at your home), its secure. If you are in a public wifi, and start a vpn-connection to YOUR server, the public-wifi-owner can't see anything except that you have a connection to your server.
Maybe also interesting:
http://www.vpnusers.com/viewtopic.php?f ... 6066#p6066