I use it, but not too often.
But I used it last year to track about 10-15 keywords for 3 sites (so about 40-50 keywords in total) and I did use proxies. I mean, you can use it without proxies but you will have to set the software to only check... I don't know.... maybe every 20-30 seconds, because otherwise google will block your IP.
So, if you have 100s or 1000s of keywords that you wish to track you definitely need proxies. But I've seen some good deals in the marketplace for proxies, I think there was one for 25 proxies for $8 / month, which is way better than what I paid for last year ($12 / month for 5 proxies)
But just so you know: the rank tracker needs to be purchased separately from SB because it's a premium plugin and doesn't come included in your SB purchase. But it's $27 or $37 one time fee, and allows you to track unlimited keywords for unlimited sites, so it's still worth every penny. The only downside that I could see is that it's pretty basic, it doesn't have cool flashy UI with lots of customizable reports and whatnot. So, if you're looking for fancy rank trackers this is not for you. But it does what it's supposed to do, so no complaints from me
