As a repairer I see the business end of a lot of mowers
"solid looking" is an impression.
You really need to get underneath and look at things like where shafts pass through plates and check for a wide load bearing surface or a replacable bush.
Look at the deck mounts , same story how wide are the load bearing points.
Look at the gauge of the metal, stick your thumb nail in the paint.
Heavy powder coating can mimmick thick steel.
Read the owners manuals and make a list of the service replacement parts then go online and price them include blades.
Look at the service points, particularly the lubrication points , can you get to them ?
Remove & replace the deck, compare one to the other & remember it is easier to do on a nice shinny showroom floor than on your lawn.
How easy is it to get a wrench onto the oil filter ?
How easy is it to fill the engine with oil cleanly ?
And the old favourite, the tranny belt, can you get to it without frying your hands on a hot muffler ?
Are the fuses easily accessiable ?