I have a general question in regards to using RAID10. Is there a performance increase when using more drives in the RAID10 - for example, going from a 4-drive RAID10 to an 8-drive RAID10 configuration? Any info related to this would be appreciated.
Depending on stripe sizes and I/O sizes you could potentially double your transfer rate (although that much of an improvement is unlikely except for sequential access to large files).
However RAID doesn't improve access times significantly so don't expect much improvement there. All mirrored RAID organizations have the potential to optimize read access time by directing I/O to the drive whose head is closest to the desired data, but except for very long seeks the lions share of the access time is in the rotational delay which can't be optimized.
So - expect better sequential transfer performance but not much improvement in access times.