Maybe you don't get my point. I think 3000+ users double check same hash numbers. I do not pretend I'm correct or that I understand. I just remember an old post of ByblePay saying multiple users "solved" same blocks in the pool.
Whatever is that botnet I think they use unique hash check code - it's open source. By my assumptions 100-200k unique hashes can beat our pool with 1 850 000 total hps. Anyway I continue to hoDL that machine in background HT cores with about 3100 hps. At some moment I'll hit 7000+ coins. Positive expectancy is because I'll not have fees and competitors aren't doing unique hash checks. If this is so then the most effective miner is solo machine. If I put 10 solo, then I'll increase the income by let's say 7 times not 10 (related to double hash checks between nodes).
While the sampling is too small to make big jumps at, I'll give you my numbers. I run 3.5 Identical Machines (2 Linux, 1.5 Win) on pool (the .5 is because one is a main pc I run at pretty low levels). It bounces around a lot, but after fees I average in the neighborhood of 250 per machine a day, which pre-fee we'll say in 300 per machine. The block reward has bounced around but well say for easy math is avg of 6600. So my one machine solo would be expected to find a block solo about once every 22 days (6600/300). I've got six other identical machines running solo. They average in aggregate about a block every two days, or put another way, a block every 12 machine days.
That said, a friend of mine put one junk and one beefy machine solo, hit a block in about a day on the junk machine and never another after about 10 days on both. Which is to say, my statistical sampling is too low at this point to make valid conclusions since prior to the last update, my solo miners in aggregate were averaging a block every five days (60 machine days per block) when at the time my pool miners were running closer to 200 per day or 33 machine days per block.
So, it remains to be seen, the main advantage to solo mining is if you're patient it pays slightly higher due to the lack of pool fees, but you could be the unlucky miner who takes twice or three times the median to hit blocks for months on end. Generally, the pool is more consistent as a function of the total hashpower in it.