The only time I've ever heard of different types of disks used in a RAID system is when people make up a RAID-0 stripe from JBOD.
Or the space cadet who created a RAID-5 with Disksuite (Solaris software RAID for the uninitiated) with 2 drives:
1 x 4Gb
1 x 8Gb (sliced as 2 x 4Gb)
Presto!! 3 x 4Gb partitions, RAID-5 configured as one meta device ...unf. This provided 8Gb of startling redundancy and speed. "Startling" being the operative word when I inherited the machine from aforementioned space cadet.
-- James -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
