The newest (really, not that new, have been in use elsewhere for ages) modulating-condensing boilers are designed for cold starts. A typical boiler doesn't like return water to be below about 130-degrees or you get condensation and longevity problems from corrosion. The newer boilers use corrosion resistant parts (SS or Al), and are designed to condense the moisture out of the exhaust, and thus are essentially immune to those corrosion problems. They thrive on cooler (just-right) temperatures and cooler return temps. The newest ones can be nearly 98% efficient under perfect conditions (hard to achieve, but mid-90's are possible fairly easily). A good indirect WH and concentrated hot water use say in the morning, may not need to fire the boiler again until you do large use again the next day. And, with a mod-con boiler, that means it may only fire once a day or so, rather than maintaining a constant temperature. This can save huge amounts of money during operations, but you do have the purchase and install costs to consider. Most utilities have rebates or incentives, but unless congress adds it in again (unlikely), there's no longer a tax credit for it. Last year, it was up to $1500, or 30% of the equipment costs, whichever was less.
An outside reset controller utilizes sensors outside and in the boiler to determine the optimum supply temperature. Running longer at lower temps (within the limits of the boiler design) mean more comfortable house and lower fuel use. Depending on the system, this may be able to be retrofitted.