At this time, I really have no interest in going fast and competing. Off road bike rides and trails may be of some interest but i can't foresee too many opportunities to do so.
I only ride MTBs because IME they are much more versatile and practical for the way I prefer to ride. I can usually keep up with even the most avid Road bikers on their decked out competition spec bikes so I'm not losing anything there. As far as I see it the pros and cons are fairly simple. You do what makes the most sense for you.
Fatter tires= Pro: smoother ride, more forgiving, harder to get a flat with. Con: it takes more energy to get started because more of the tire is touching the ground ........................... tires available for streets, trails or both
Skinny tires= Pros: takes less energy to get started and you're able to go faster sooner (I think they may be available in Cyclecross treads as well)
Cons: harder ride, not forgiving, easy to pop and easy to damage a rim, harder to stop in the rain because of less traction (if you're riding nice & easy then it's not a factor), harder to be ridden on imperfect terrain
If you live in a walk-up and have to carry your bike upstairs than a lighter bike or folding bike is pro too.
A Bad Boy or a Quick CX (Cyclecross) can be used for both. When I ride in the city, I just throw on my street/light trail tires and pump them up to the maximum psi for more speed and better road traction and if I hit light trails all I have to do is release some air like when I'm jumping the boulders in Central Park. (if you forget to remove pressure and go offroad it is easy to get lose traction and get hurt... I got reminded the hard way)
Another good option is the Cannondale 29'er. Basically the same as a Bad Boy or Quick CX but because of the larger radius on the tire, you can roll over almost anything with ease. It's hard to imagine what a difference it is until you ride one.
I know MTBers that traded them back in because it was too easy to ride mountain trails because the bigger tires would steam roll over things so easily that it was no longer a challenge for them so they went back to a standard 26'er.
In fairness it is easier to "Taco" a rim because the rim is larger as well and the spokes have to support a larger diameter. Unless it's a higher grade rim or you take it easy. 29'er rims are the same as road bike rims (700c) but accept a wider tire as opposed to a skinny road bike tire.
crazy, that there is as much as a learning curve with choosing the right bike as there is in our fish hobby.:smash: