What changes with a condensing tankless vent route?

Cooler exhaust can mean a condensing model permits vent materials that a hotter-exhaust unit would not, which may help with a constrained route. It doesn’t automatically make the route easier, though: approved materials, length limits, and fittings depend on the specific model, while the route and termination may also have other applicable requirements. I’d compare the proposed path against each candidate’s installation instructions rather than assume the existing route will work for either type.

Condensing units produce condensate that needs an approved disposal route; whether neutralization is required depends on the model instructions and applicable local requirements. If the drain is far away, getting the condensate there can add routing work or require another approved arrangement, so I’d treat drain access as part of the installation comparison rather than a minor afterthought.

I’d treat easier approved venting as a more immediate benefit than the efficiency gain, since it can affect whether the route works at all. If condensate disposal is also straightforward, the efficiency advantage would strengthen the case for condensing; if the drain adds substantial routing and upkeep, I wouldn’t consider efficiency alone enough to settle the choice.