We just recently replaced two SANs with some 3par arrays.

Most SANs these days seem to work with the disk pooling method as it does seem to provide generally good overall performance. I did about a month of testing before putting anything prod.

Make sure they turn OFF thin provisioning for all your SQL disks this yielded about 12-15% faster write speeds, If the array supports it ask them to optimise the LOG files and TempDB files to the outer most tracks on the disks this gave another 2-4% boost in our situation.

Also in our situation we found that generally Raid 10 was about 5-10% faster then raid 5 despite vendors sales pitches that Raid 5 is basically as fast as Raid 10.