The precision depends on how accurately you can hit a button. Much more useful for production out in the field. Finally, an extremely minor convenience factor in Sony's favor. In pause mode, Sony has a much quicker fast forward mode, several times the rate of the Aiwa. Sony's high-speed fast forward can be real handy if you are searching for something in a very long track.
Cost is always an issue, so here is a brief rundown.
Marantz recently introduced a professional quality portable MD recorder, the PMD650. It is no doubt more robust than the consumer machines, but whether it is worth 3-4 times as much would depend on your needs. So in summary, the minidisc format is a winner for the radio journalist. The audio quality is excellent, the format boasts a number of really useful convenience features, and the cost, particularly in view of the added value, is quite reasonable. Choosing the right MD for you depends on your particular needs.