My :2cents:
As far as longevity, I believe diesel wins hands-down. It seems that with diesel longevity, the turbo is the weak link and one just has to be prepared to replace them at some point. (Unless it has no turbo!) Yes turbo boost power, fuel efficiency, emissions, power, etc..; but IMHO, turbos are a trade off.
As far as 32hp (gas) vs. 25hp (diesel): They probably measure that 32 hp with a wide open throttle (or close to). It's a question of do you want horsepower, or torque?
The torque the gas engine produces (and horsepower) may drop off significantly when not wide open. The torque a diesel engine can produce typically does not drop off as sharply as a gas engine at lower rpms.
Remember that horsepower= torque x rpm. "To make more power an engine needs to generate more torque, operate at higher rpm, or both." So a low torque motor at high rpms (gas) can be advertised to have more "horsepower" than a diesel motor, that although it has more torque over a wider range of rpms, it has a lesser (top end - maximum) rpm, and lesser "horsepower".
Basically: Using horsepower in a gas vs. diesel comparison is comparing apples to oranges.