Higher octane does not give an engine a better performance. It justs burns better and reduces engine ping, but that aint common in mowers.
Yep ... you are Right about octane... there are a few around that think higher octane is equal to higher performance.... But Like you said, that is Not the case, you Only need Just enough octane.
And a few other things to be expanded on, (not just to argue about something that someone is trying to sell)...
the safety issue, and Pooling... Propane is Heavy, it Always will pool, and will accumulate in the lowest place, it is an invisible gas, you will never see it... Inside it just builds up on the floor, Outside it 'May' disperse or it May go into the closest basement, just depends...
It
'can' be very safe to work with, I farmed for Years using mid size tractors on propane. I do "know" the gas & my gasman... but I also know how a lot of folks handle fuels.
If someone is mowing and they need a gallon of gasoline or diesel to finish a job, not a problem, they can dash to a service station, usually within a couple blocks, and get a gallon or 2, finish up and be done... run low on propane and you will not just grab a 5 gallon jug and find a handy source...
Delivery is not a problem... I still buy propane in bulk, usually around 700 to 800 gallons at a time. Not Many users of gasoline or diesel have delivery. It is Just too easy to pick it up As you need it.
Cold starts on propane are Less than ideal, I know they are better today than they were... but Still not perfect.
Over all if I were looking at a new machine for commercial or even large acreage, I would look First at Diesel, then Gasoline but I would be hard pressed to consider propane.
I Know propane exchanges are more readily available today
for a BBQ grill, But that is likely the Most expensive propane you will ever buy, that 20 lb bottle is sold by the Pound, Not the gallon. and you can easily Run out early in the cook out...
As for the "old-wives tales" about propane horrors...they sill happen.