I'm not questioning the recommendation of an accumulator with multiple fixtures, but I would like one in my Boler even when using only one fixture at a time. If I open the faucet fully the pump runs continuously and all is fine; however, if I turn the tap only partway to get less flow the pump cycles frequently to maintain its set pressure at the lower flow rate. That's normal behaviour - it just isn't pleasant.
An accumulator stores some water under pressure as a reserve to smooth out the demand on the pump - with an accumulator the pump should run about the same amount of time, but in longer and less frequent cycles, which I assume is easier on the pump and would certainly be easier on my nerves, whether or not the reduced starts actually mean less energy consumption.
The alternative is a variable-speed pump. I found these when investigating potential replacement of my old (maybe 1979 original equipment) SHURflo. I'm not sure why people are using the Nautilus
marine product (maybe because it is the smallest unit they have for potable water?) but in their RV products
(and in the marine line) they have an Extreme series
including variable speed units, which speed up or slow down to match the water flow, and thus do not need an accumulator. This is what I plan to get when/if my current pump dies. Since even their smaller unit is larger than we might need, electrical
capacity might be an issue, although actual energy consumption should be low since the power draw is matched to the water flow rate demanded.
Speaking of marine applications, a friend of mine had a sailboat which deliberately had no electric pump. He had the power but he wanted to discourage excessive water consumption: when you are manually pumping, you don't pump when you don't need to. He had a foot pump - not hand-operated - so both of your hands were free when using the sink.