If going solar price out a Versa Hydro Solar solution before commiting to an Alpine 80 + solar solution. The Versa Solar is a fully integrated single tank system, with very little difference between the 80 gallon Versa and an 80 gallon Versa Solar, beyond the extra coil for the solar loop and some extra controls. With 80 gallons of buffe it would guarantees even longer minimum burns in space-heating mode.
Even if you never install the solar end it's efficiency would be as-good. It's a matter of the up-front costs of an 80 gallon Versa Hydro Solar with an as-yet unimplemented solar loop relative to the proposed non-solar solutions up front. An 80 gallon solar tank by itself is a pricey piece of hardware, and adding that to an Alpine-80 + buffer solution would mak for a more expensive total package.
Not to mention, with either a solar or standard version of the Versa most of the system-integration is pre-engineered, whereas with the Alpine 80 you're at the mercy of the system desginers/installers, and the quality of the design & commissioning a full-custom system will vary. It's pretty hard to screw up with a pre-packaged pre-engineered system.