LPG does run hotter making the valve seats a little more vulnerable. Most manufacturers that do a factory fit gas system (LPG or CNG) will uprate the valve seats, but a modern engine built for unleaded probably will be OK anyway.
One big advantage on a wear front with LPG is the absence of bore wash. With petrol (gasoline) in a cold engine the fuel condenses on the cylinder walls, washes off the oil and dilutes the oil in the sump. With LPG there is no condensation, no wash, no oil dilution. Oil tends to stay clean for much longer.