Ken's birthday present was a day's flying in a Cessna Chancellor. The 414 is a pretty big small airplane: twin turbocharged engines, 6750 pounds, comfortable seating for seven people. It's a small plane compared to commercial aircraft, but it's big and fast enough that it can be used for charters. And Ken and I got to fly it. Well, our CFI flew it, but we got to play along. It's a lot of airplane.
The FAA requirement for me to be legal in the Chancellor is laughably small, 10 hours of flying time to learn how to recover if one of the engines fails. That's a crucial and difficult operation but apparently it doesn't take long to pass the required skill checks. But the MEL is the least problem; I'd need a lot more time and experience before I'd feel safe. And the insurance companies want some 100 hours in a similar plane before insuring a pilot.
The main challenge of flying a bigger plane is it has more energy. It's heavier, it's faster, it flies higher. It takes experience, planning, and fine control to go from 200kts at 18,000' to stopped at sea level on a 2450' long runway. More energy is more fun, of course, particularly being able to climb at 1000 feet per minute or more above the Sierras. But everything goes faster, and heavier, and you have to know your plane.
The other big challenge is systems complexity. Bigger planes have more stuff: cabin pressurization, de-icing, turbochargers and intercoolers, complex fuel distribution, etc. It all has to be managed by the pilot, mostly manually. Every new task adds pilot workload. The only way to develop that extra bandwidth is experience.
The fact that there are two engines out front seems the least of the challenges. There's a bit of extra work tuning the RPMs so they run harmonically but other than that a twin is all gravy. More power. More lift from the prop-wash over the wings. And a great view out the nose with no engine or prop in the way. Babysitting the turbocharger temperatures was more work than worrying about having two engines. As long as both of them are working.
I'm not in a hurry to move up to a twin. I just started my instrument rating, that's the next big task. Then more experience flying, only then maybe something bigger and faster.