If it is crashing for you every thirty seconds or so then I wouldn't recommend buying it - you'll never get anything done. I've got the GameSpace is about to crash message about 8 times, and it has always been because I've created an edge where there should definately not be one (for example) and have been able to fix it.
To be honest I've only ever used the Save Scene function (apart from when exporting) as I do all my work using the New Project and Insert Scene functions in the respective libraries - but saving as a cob seems to work fine for me... but I don't see why you would need to use it for work in Blitz unless you wanted to created an animated movie.
To be honest I've only ever used the Save Scene function (apart from when exporting) as I do all my work using the New Project and Insert Scene functions in the respective libraries - but saving as a cob seems to work fine for me... but I don't see why you would need to use it for work in Blitz unless you wanted to created an animated movie.