I view one of the primary differences between the two in that aspect of reset. EI requires it at high levels and ~weekly, rightly so, whereas PPS tends to be more flexible, in frequency and quantity, as it tries to more closely match uptake with dosing. This a major factor and circles back to the water change frequency thread we were all discussing last week.
They both have fixed-dose starting points, which is what the calculators use, but both philosophies recognize the desire/need to be flexible. I do believe that, despite flexibility around their mean, they remain quite far apart on expected water column nutrient levels.
I consider myself much closer to the PPS philosophy, in recent years, after many years with EI. @Greggz
: it would be interesting to hear which approach you believe you are closer to now.
I follow many of the best tanks from around the world, and have the opportunity to communicate with many of them to learn more about their methods. I am talking about tanks that are similar to mine in that they are very plant centric, rather than hardscaped dominated.
The funny thing is not one of them would refer to their dosing as EI or PPS. They just refer to the numbers that they use. EI calls for 22:4:22 NO3:PO4:K and 2.0 Fe from micros (was at 5.0 just a few years ago). I don't know of one that doses at that particular level. And almost all pay very close attention to Ca:Mg levels, which is not a focus of EI.
There is one fundamental that is almost universally true of the most successful "Dutch" inspired tanks from around the world. Like you alluded to above, it's regular large water changes. IMO, that is easily the most common denominator regardless of dosing levels.
For me, I have tested loads of dosing levels over the years. My conclusion is that dosing is the least important of the fundamental things that the best tanks share.
Much more important to get light, CO2, and maintenance correct. And of those, maintenance may be the biggest common factor. The most successful people work harder at it. And that includes trimming, pruning, and plant mass management.
If you get everything else right, you can get by on a wide range of dosing. At that point dosing is really fine tuning things. If you don't get everything else right, even the most perfect dosing scheme won't save you.
The other thing to keep in mind is to always look at the particular plants in a set up. A tank full of Rotala's is a lot different than a tank full of Ludwigia's and Limnophila's.
As for me, current dosing is 10/3.5/15 and Ca/Mg at 20/8. Micros are custom at 0.525 Fe. And my tank is pretty much on auto-pilot right now. But the reality is most of that is not due to the dosing, it's due to everything else.