The conversation that I had with s4nt0S, in which he informed me of a cvonversation that he had with Loopline, who in turn checked with the authors of ScrapeBox, @s4nt0S told me that proxies checked by GSA Proxy Scraper should not also be run through the Scrapebox proxy check. Never one to take information given to me, no matter how reliable the the source, I spun up a new VM installed version 1.10 of GSA Proxy Scraper and grabbed the first 113 GSA passed proxys and dumped them into Scrapebox and tested with 8 keywords. As public proxies are want to do, the proxies burnt out fairly quickly, but they did function properly without prior testing in Scrapebox.
I had decided that I would also test this in GScraper. Unfortunately, about this time I found that another was poaching on my business name. So, I blew him out of the first three keywords I target for my physical business, and blew him out of Google entirely for some of the keyword. When this occurred, I decided that I would target other keywords and fired up GScraper. I pulled about 320 proxies from my personal proxy tester, dumped them into GScraper, Used the merge function of Scrapebox to merge backlink scraping footprints to the first few pages of links from Google for some keywords. I ran GScraper at 32 threads, which is my typical 1:100 ratio. 195 hours later I had completed scraping 68000 key terms for backlinks. And this allowed me to begin testing the method related to me by s4nt0S.
I spun up another Windows 10 x64 VM and installed GSA Proxy Scraper v 1.16 trial. After I collected 947 GSA passed proxies. I dumped them into GScaper and used the internal keywords that Gscraper has. I set 90 thread and started the scraper. Gscraper began scraping at about 5600 URL's/minute (93 url's/sec.) Gscraper required twenty minutes of scraping before the scrapes dropped below 5000 URL's/min. (83 url's/sec.) At the end of twenty minutes I ended scraping with GScraper.
Version 1.16 seems to function better than version 1.10. It did, however crash one time in Windows 10. I am presuming this is due to Windows 10 being beta rather than any fault with GSA Proxy Scraper.
With the tests I conducted, it is now my opinion that for scraping public proxies GSA Proxy Scraper is a fair bargain.