only use public proxies in gsa

i was wondering to use only public proxies in gsa so what will be the results if i only use public proxies ?

I would not use public Proxies in Search Engine Ranker, (GSA is the company name), Have a look at this test by Ferryman comparing Semi Dedicated proxies against Private proxies.

You will get much less successful results from public proxies. Rather go for Semi proxies or preferably Private proxies.