Depending on the school of thought you adhere to, it's a good idea to set the WH thermostat to 140 or so. This requires a tempering valve on the outlet to protect you and your family, but does two things: maximizes the hot water available and is hot enough to kill many nasty bacteria.
It depends on the boiler design and control circuits. Mine monitors the outside temperature, the return temp, and a call for heat, then adjusts the supply temp to meet the circumstances. Depending on how cold it is outside, it might only run to 120-degrees, or on a really cold day might go up to as high as 190. It has a modulating burner that can throttle down to 20% of maximum and can approach the high 90% efficiency. If your boiler can handle the cold starts, in between calls for heat, it might cool off to near ambient. You probably want to keep the temp at least a bit higher than your WH temp setting. Some only have a very small supply of water that it keeps hot, so it really isn't using all that much.
See what some others have to say and I'd consider calling the tech people at the boiler manufacturer's place.
What some people have done here is add an electric WH after the indirect. Since it is supplied with heated water, in the winter it almost never runs, and only runs as the water stored in it cools off. In the summer, shut the boiler off and rely on the electric. Now, you'd have to do a trade-off of the costs and space to install this verses the energy to run the boiler.
Since the SuperStor is quite well insulated, you might consider a timer, and only turn the boiler on for the normal use times. Don't know how well the thing would like the cool-down, heating cycles.