Now that I read more of the posts, I think most all of the manufacturers make both 2wd and 4wd options. Maybe your local dealers don't carry both, but I have been working as an OHV/ATV mechanic for the past 15 months and I have seen plenty of both. Maybe the 2wd option has a different model name than the 4wd model but for 4 wheelers there are usually both options. (just maybe not in all model names). Side By Sides or UTV's are usually all 4wd capable, but only if you select 2wd or 4wd. Even new 4 wheelers are available in 2wd options, depending on the model name, and many are capable of both 2wd or 4wd depending on what you select with the switch.
But, if you don't activate the 4wd option your front axles wont engage. Yes, the front driveshaft will be "powered" but the front differential will be unlocked and power will not be distributed to the front wheels.
Now, not to pick on sourdough for the Can Am choice, Can Am (Bombardier) are more difficult to work on because most every bolt has a nut on the back side where most every other brand has that nut welded to the frame or other body part. Is that a bad thing? No, unless you are working on them because it will be more effort, a bit of a pain in the back side, and will take longer. Also, the cooling system of the Can Am is lousy.... if you live in a desert area with high summer temps. The only thing in our experience at the shop I work at that is worse is a John Deere. Although I think the Yamaha Rhino 660 are 2nd in poor design only because more of them are sold than the John Deere. Rhino's may be good for the first couple years but we have had more of them in the shop over the last year than any other make or model just due to poor design. I know that when a Rhino comes into the shop there will be complaints about the fuel system. I know that when a John Deere comes into the shop getting parts will be about as difficult as remounting their wheels that have bolts instead of studs on the hubs that use lug nuts. Trying to align the wheels to the holes in the hubs while trying to start the bolts into the holes on the hubs is the worst part of my job.
Again, I defer back to my previous post that every ones situation will be different and depending on their use and terrain the opinions will vary like belly buttons. It is about impossible to determine what will be best for you in your area and for your use. Comparison? My huge mega cab Dodge Cummins 6.7 diesel 4x4 gets better mileage where I live than any of the other 5 vehicles in our family, including the small cars, simply because the constant up hills require the smaller engines to need more throttle but on the down hills we all can coast with our foot off the throttle. An 8000 pound truck gets better mileage than a 3000 pound car? Things that make you go Hmmmmm.
