Since you guys mentioned the Tucano, most of today's high peformance prop planes are not piston engined.
In fact, these planes are "almost-jets", using a turbine engine to drive the propeller.
The disadvantages of these engines are expensive maintenance, fuel consumption and slower response to power changes than a piston engine because of the turbine's spool up/down time (however, this is also found on piston engined planes if they are equipped with a turbocharger, like the P47 for example).
The advantage is that you don't need superchargers and turbochargers if you want to operate at higher altitudes, because a turbine engine is inherently designed to compress the air before burning the fuel-air mixture. This saves space and weight for other stuff (turbo-prop engines are very straightforward compared to a high performance piston engine equipped with superchargers and turbos).
Part of the reason for the WWII piston fighters reaching their peak was just that, the materials used at the time couldn't be pushed further to guarantee adequate performance without some kind of drawback to cancel out the gains (eg, increased weight or complexity/servicing requirements) at the altitudes a turbine could operate. Since altitude controls the fight, jets took the lead.
Even today, most of the piston engined general aviation aircraft use horizontally opposed engines (the boxer-type engines you see in a porsche car) of much lower horsepower than a WWII piston engine and only a minuscule percentage of these planes is fitted with superchargers/turbochargers. If people want to build an aircraft capable of flying at high altitudes or with a lot of spare power, they use turboprops.
This has even gone as far as re-engining old but tough and proven workhorse planes with turboprops, like the DeHavilland Canada Beaver and the Grumman Goose. The engine used in these two, the ubiquitous Pratt and Whitney Canada PT6A series of engines, can be found on dozens of different aircraft (the Tucano as well) and it generates so much power compared to its size that it can easily be fitted in smaller airframes or designs that were never meant to go that fast.
The end result is having an aircraft with a Vne (never exceed airspeed limit=plane breaks up if you go faster) of, let's say, 150 knots that can suddenly go faster than that in level flight. It might seem dangerous but it's not, first of all because pilots don't usually try to exceed their Vne and second, the added power is used in a way that doesn't add speed, but versatility in the form of improved climb rates.
For example, when operating from an improvised landistrip at a high altitude, a piston engine will have trouble at higher altitudes but a small, light plane with STOL characteristics and turboprop power reserves can be loaded and still achieve 1000ft/min climbs. The reversible propellers also add a lot to this kind of operations, making it possible to touch down at 50 knots (80km/h), apply brakes and reverse thrust to stop at no time, making even a small unpaved field in the mountains into a suitable landing strip. And when it's time to depart, you can go full power for the take-off and literally hang the plane on the prop without fear of stalling, making it all that easier to to clear that row of trees or the ditch at the end of the improvised runway.
Since these engines also run at way reduced power during cruise (in order to stay below Vne), this translates into less engine stress and increased service life/time between faults.
If i ever had the money to buy a plane for personal fun i'd probably buy an amphibian or bush plane, something like one of the improved and reengined Piper Cub variants, or something a bit more vintage with a supercharged wasp junior piston engine (you can't beat the sound of an air cooled radial). However, if i wanted to do business with a plane i'd buy a turboprop one.
Damn, i got totally sidetracked on this one
