There are some shmups which are better on the PS1, for Dodopachi on the the Saturn the graphics get pixely on the explosions. There is some slowdown but the arcade had a little bit too. There are some parts better on the Saturn such as having a tate mode and two players able to have different ships. Plus, it is cheaper. In the end, both versions are worth playing.
If you are looking for just R.O.B. himself, importing one from the US is probably the cheapest way. They are practically identical to the EU version. I got one from the US the other year for under £40 (exclusing postage).
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