The gyroplane without a horizontal stabiliser your friend refers to was the Aircommand design and it had a pretty horrific accident rate. Things got so bad in the mid 1990's UK CAA commisioned Glasgow university to do a study into gyro flight characteristics using a modified 2 seat Montgomerie Bensen machine which was heavily instrumented .The more recent designs solved the problem of centre of thrust line/c of g and size of horizontal stab required which has reduced the incidence of powered push over . Still see lots if accidents reported but it seems to be more on a par with other ultra light types these days .BG