Saabs probably don't blow more head gaskets than most turbocharged cars, although turbocharged cars as a group probably blow more head gaskets than do more mundane cars.  Turbocharging leads to high compression pressures and high compression pressures can lead to head gasket problems.  The same can be said for engines that use aluminum heads, as does Saab - aluminum warps a lot more at extreme temperatures than does steel.  So take care of the cooling system.  Every couple of years: Flush the system and change the thermostat. And use Bar's Leaks as recommended.  I FIRMLY BELIEVE THAT IF YOU MAINTAIN THE COOLING SYSTEM PROPERLY, YOU WILL NOT HAVE PROBLEMS WITH THE HEAD GASKET.  NOT EVER!  A genuine Saab thermostat costs maybe $20 to $25 ... can you spare that much every couple of years to save a thousand dollar head gasket job?  Think about it.  The problem is that thermostats can stick or fail outright as they age (particularly the wax type that Saab uses).  If it sticks closed just once and you don't notice the temperature rising until it's too late, you're probably going to be staring a head gasket job in the face.

Symptoms: Coolant level drops slowly over a period of time, but no leaks evident; sometimes, a bad miss for the first few seconds on initial startup (water in the combustion chamber); in extreme cases, white exhaust "smoke" (steam); low compression reading on one or two cylinders.

Preventive maintenance:  I think the best preventive measure is to flush the cooling system and change the thermostat every couple of years.  A close second is to use Bar's Leaks (liquid, in the silver bottle) in the cooling system as recommended by Bar's Leaks.  Bar's Leaks Web Site  And third, try not to drive the car at 140 miles an hour for extended periods.