A quick update. I am going to classify the crash/BSOD as "machine specific". It was solved by changing a BIOS setting, although then again no software except Serpify ever triggered it (not even CPU/memory stress test utilities). But still, resolved without any upgrade so I'm giving a pass.
I also do extensive server side logging and alerts and can confirm a good diversity of origin countries (assuming that's what you want).
One thing I noticed was that the number of client JS errors on my site have really shot up (I have a client side "black box" utility to capture them from every visitor). Whenever I manually investigate, I see they are nearly all from Serpify clients (pretty obvious due to the abnormal user-agents strings, the entry pages, they come from Google, and they browse in weird directions). My *guess* is this may be caused by a bunch of old Windows 2003 or 2008 VPS with old IE?
Another thing, and tied to the above, is that the browsers *do* seem fingerprint-able, i.e. if Google wanted to put effort into detecting it, they probably could pretty easily. It wouldn't be so bad if the "botnet" was comprised of 100% residential computers running updated IE.
Another problem is I've started getting captchas from Google when searching from my regular computer on the same network as the Windows box running Serpify. i.e. Google does detect automated activity from my residential IP.
A final concern is how easy it is to generate utterly unrealistic CTRs. i.e. there's no check in place stopping you generating a 99% CTR on a term you only rank 199th for. I'm trying to be careful, but it's so easy to not be careful that I worry this will quickly get flagged to Google by many users. If I were serpify, I'd want to stop people blowing themselves up in front of Google and drawing attention to the whole service. Not to mention that unrealistic CTRs aren't likely to help you at all. It would actually add huge value if serpify themselves took control of the frequency of searches - based on the existing SERP rating - and perhaps only allowed people on the most premium of plans to go nuts and set their own limits.
So my conclusion so far: As best as I can tell, this does work, if volumes and CTRs are done right. But, I worry this will blow up soon unless (a) there's greater diversity of browsers, (b) huge reduction or elimination all the legacy IE, and (c) limits in place to stop people generating unrealistic CTRs. But until that happens, I'd definitely recommend this.
We were facing lot of personal & professional issues recently because of which we couldn't concentrate much on our product Serpify. Hence the support tickets & thread were not been responded. But we are back now and we will resolve all your issues soon.