I'm not sure how you can make these claims. To fully test your theory you would need identical rigs, one mining nicehash, the other nplusminer during the same period.
Yes, to FULLY TEST this I would need to go through a lot more trouble and buy another 6x 1080 rig, but seeing as none of you people are paying me to do any of this you'll just have to settle with me first doing a concurrent comparison between NiceHash and Zpool/NPlusMiner using my two rigs that are identical - each with a single GTX 1080 - and then use that as a baseline to establish relative profitability scaling when I run NPlusMiner on my 6x rig. So I will then be comparing a single GTX 1080 running NiceHash vs. 6x 1060 running NPlusMiner which I freely admit is not the most scientific way of doing a comparison, but it is "close enough for government work" as the old cliche goes.
Ah ok, I guess that is my fault for not fully reading how you were performing this experiment. One other variable though is that you are using zpool, which is notorious for payingabout 20% less than it says it will. Numerous threads and accusations about it. Currently my bat file is running all 4 of the pluspools and so far zpool hasn't been the most profitable pool a single time. It might be worth running this experiment with blazepool.
Well, I'll admit it is unreasonable to expect everyone to read every post by someone before replying to them. And I'm well aware of the many complaints against ZPool which is why I tried them out in single algo, convert to anything besides BTC mode first; it was only after switching to multi-algo, convert to BTC mode that profitably went straight out the window.
In the end, I think @dragonmike has nailed down the real reason for such terrible profitability with these multi-algo, auto-convert pools, and that is what is hot right now might not be so hot when it finally gets shunted off to an exchange for conversion to BTC (especially with such crap exchanges like stocks.exchange - I sent some BTC there 7+ hours ago and it still hasn't shown up in my wallet, while another BTC transfer I did to a person here went through almost immediately...).
I think bitcointalk has conditioned me to assume 75% of the people have no idea what they are talking about, so anything too long winded I skim over

To be fair I have still read complaints about zpool when you get paid in the coin you mined. In that case I think the core reason is that you can specify a currency, but you technically cant specify the coin you want to mine, so in the end its still converting it for you. No doubt these auto-convert pools are dealing with crappy exchanges and selling regardless of how the charts look.
In my humble opinion I think these profit switching scripts are pointless for a single pool. The real benefit is when they monitor multiple multi-algo pools. Not every multi pool mines the same coins and algos, so automatically switching between what is most profitable is in theory beneficial. Either way it would be nice to see this nplusminer continue to be developed; Its the first one I've seen that at least tries to add in some prediction logic.