OP you need to properly separate these proxies by other criteria as well. Are some of these proxys socks5 for example? Are they high anonymous, semi-transparent, do they bleed your actual local IP? This coding may slow down the overall functionality of your system, but without it these proxys can be quite questionable to use in certain SEO instances. The fact that they passed the google test doesn't mean they are anonymous. Additionally most proxy testing software will identify proxies as L1, L2, L3. These are important considerations.
Now that I've said all that, I'd also love to beta test this for you, and I'm comfortable for my uses without the additional coding requests I suggested above. Let me know if you have any more room for beta testers, and thanks for putting this together. Looks great overall, particularly at a $12ish monthly price point. Good luck when you move to sales mode!