Performance in chunk vs. chunks?

My boss from the old school is concerned that a heavily used DB spread across multiple chunks on separate partitions in the same disk will suffer performance degradation as compared to a single chunk for the whole DB (obviously a large chunk, about 150 Meg). My cohorts and I have no information to confirm or debunk his suspicions as this is a new product for us. Has anyone experienced said degradation (or perhaps enhanced) performance from spreading a DB across multiple chunks in separate partitions? Any experiences or even opinions are very welcome. Thanks in advance, Jason B. Hendrix jbh@dsc.com -- If Mr. News spews so, it must be true.