There are a few details anyone would need to even think about answering this question.
"With today's energy costs" - If you know the future (e.g., next fall) energy cost you would be making so much money on the futures market that the question would be moot. Calculations for ROI need costs to evaluate.
The 97% modulating boilers are condensing. They use the return loop of the circulating water to cool exhaust gases to the point where the water vapor condenses to recover the latent heat of vaporization. If the required temperature of the heating system return water is above the condensing temperature, it will not get to the 97% range. You did not specify what your heating system is. Radiators, baseboard, in-floor radiant, etc. (I assume you are not talking steam). Each of these approaches has different water temperature requirements. You need to know your heat loss for the structure, what the required temperature/flow is for your specific installed heat exchangers to maintain room temperature. Your boiler must be sized correctly for efficiency.
One thing you want to do, if everything else looks like it will work, is to use outdoor reset. This is a sensor that measures outside temperature and adjusts the temperature of the water provided by the boiler. I think the Veissman's come with this but I am not certain. They can certainly use it. The ratio (curve) is in a table in the microprocessor running the boiler. These curves can be adjusted to optimize a particular system. Some vendors and heating contractors will not provide the information needed for the owner to access these functions. If you want to fiddle with it chack before you buy something.
As with many things, the answer is not simple and requires other answers first.