I have a 2020 Can-am Defender with the factory cab. There is a large cab air filter up under the hood that filters the air for the cab. And yes, the cab is so tight that to shut the door completely I have to have a window cracked open. What I really like about it is that the windshield is hinged at the top; if I want more airflow in the cab I have the option to open the windshield about 6" - or open it all the way. The windshield is held up by struts and during the summer I drive that way all the time - yes, the owner's manual says it is perfectly OK to do so. Here's a shot of my windshield open all the way:
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I did a lot of research before ending up with the Can-am. A factory installed cab - covered by warranty - with door windows that roll up and down just like in any car was important to me because I wanted an all season vehicle. Not just when it is cold and nasty - but out here in the desert dust is a problem - I see guys out here with no cabs wearing special dust masks/respirators/goggles to keep from breathing thick dust kicked up by the machine or nearby machines. Only the Polaris Ranger and Can-am Defender offered a factory installed cab with roll-up windows (didn't consider Kubota or John Deere as the "recreation" part was important to me). Having to work with the two Polaris Rangers in my Search and Rescue unit convinced me I didn't want a Polaris. As far as drivetrains - my research showed that all these side-by-sides have problems, including the Honda. Honda had to replace a lot of clutch packs (their dual-clutch transmissions) because they burned out. And most of the guys I know who own belt-driven side-by-sides carry a spare belt. The problem with both the Honda system and the rest is primarily the owner - the driver. And that is because they don't use low range when they should. Climbing hills or towing or even just driving slowly in high range burns out the Honda clutches and burns up drive belts in the other machines. My Can-am owner's manual specifically states to use low range if the machine will be driven under 15 mph. Consequently, when I am poking around in the mountains there's days I rarely get the machine into high range - I keep it in low range and let the engine rev.
I carry a spare belt; if I ever needed to I bet I could change it out on the trail in a half hour, taking my time. Very easy to do. Changing a clutch pack on a Honda is not something you'd want to do on the trail.
Personally I can't wait for someone to come out with an electric side-by-side with a range of about 200 miles. No transmissions or belts to worry about. And no engine noise!
One other thing I found in my research that Honda Pioneer owners complained about a lot - engine heat radiating into the interior, making almost it unbearable inside on a warm day - and that's with no cab.