Just to wind up a few of the 'you must have a check ride first' posts
Over my long and not very distinguished flying career I have 'self converted' approximately a dozen times without incident
The reason - most were single-seat gliders and three were single-seat PFA types with no 2-seat equivalent.
The secret was laid down by Derek Piggott in assessing the likely handling of the aircraft and in being prepared before committing flight. This will include talking to pilots who have experience of the type and a decent period reading the handbook and learning the numbers.
As with all aircraft you start slowly and methodically and build up gradually the flight envelope you are happy to live with. It is, after all, what test pilots do
I try (not always successfully) to do something new on each flight and avoid taking the aircraft for granted until I am happy I know how she will react.
I am more worried by those PPLs who learn on a C172/PA28 which, lets face it, flatter your skills, and think they are pilots. Most never move out of their 'comfort zone' or take any further instruction/coaching.