I want to share my experience about these proxies. I used them in past periodically, and last 2 weeks they are my primary proxies. I use Europe and Russia proxies. I create up to 15000 TCP connections simultaneously with average 30 Mbit/s incoming and 5 Mbit/s outgoing traffic. May be these proxies can even more, but my server can not, so someone else may experience even better speed.
IP addresses are rotated on regular basis, IP rotation speed is not the fastest on the market, however, fast enough to avoid blacklisting all of them by target website.
Pricing is very affordable. Many providers that have IP rotating proxies limit connections count, so software that works via HTTP protocol and creates a lot of short living connections simply can not work; 1 web browser emulator thread can create 10 short living HTTP connections to load images, CSS, etc, and such connections will be overpaid if provider limits connections count. With Rsocks, however, we have not such limit.
Conclusion: if you need fast, stable proxies with huge IPs pool and with affordable price, use Rsocks!