Haha - good one Norm. I have to say I concur with your thinking - I think the average person treats their mower, rideon or not pretty horribly.....then wondering why it either dies early &/or is always having issues. I've no doubt 99.9% of users on here are in the minority as we understand simple common sense maintenance which keep our gear running well for yrs.
So I will take your advice onboard - as my past buys with mowers have generally been the 'both legs and wings' category far too often - trying to sniff out a bargain and then discovering that the previous owner had done all kinds of horrors to them. While I can struggle through (as shown by my threads) with smaller mowers on this stuff - with a larger rideon it'd be pushing things as my mechanical abilities are nothing like yours.
The only other machines I've given much consideration to are the walk behind mowers/slashers. Again they're pretty rare to see for sale Deutscher make a 22" and 28" cut version - thing is they seem a tad slow. Top speed being 3.6km/hr for the 28, which is likely the only one I'd consider as a 22 is basically the 550 Pro size.
They seem pretty bulletproof though as a design - walk behind slasher/mowers in general - I'd imagine they'd be less prone to 'issues' than rideons? As you'd not have a persons weight on them and moving at a much higher speed etc?