some machines have an electric blade clutch rather than a belt tensioning design; some collect the grass better than others.
If second hand, steel cutter decks rust out and are expensive.
Mine has a mechanically engaged blade clutch, which is very little different in design to an electric type - so I wouldn't choose one over the other - Called a PTO (Power Take Off). Second hand, the blade/deck/PTO clutch on mine soon began to exhibit problems, and replacements were a silly price, so I investigated. What I found was it was metal against metal friction, whether it was designed to work this way was not clear, but I decided to to try fitting some material between the metal clutch plates, to provide some friction. I cut a large piece of old gasket material to the shape of the plate, which I then super glued in place on the metal plate - glued just to make sure it stayed put long enough to reassemble it. Once my botch up had bedded in, it worked absolutely fine and has worked for several years since. The clutch uses a spring to push the plates apart, and three ball bearings in grooves to jam the plates together.
Grass collection is hopeless - grass is blown via a duct, which is in the middle of the body, going up and over the back axle. If the grass is anything but very dry (in the UK??), it sticks and chokes the duct up. Collector is on the rear, which I gave up using long ago, because of the constant need to take it off to clear the duct. I suspect the side discharge type may be less of a problem in this respect.
Drive is via three V belts, leading to rear axle, variable speed like the old DAF variomatic.
It's my second one, both have had very thick and tremendously heavy steel cutter decks, rust has never been a problem.