Difference between complex layouts - RAID5 and RAID 50/RAID6 and RAID60

Let's compare these RAID levels:

• these RAIDs have the same fault tolerance, however in RAIDn+0 arrays the chance to survive more disks failure is greater (but not 100 %). You can easily estimate and compare probabilities to survive multiple disk failures for different array layouts using free RAID failure calculator. 
• RAID5 and RAID50 survive one disk failure with 100% probability,
• RAID 6 and RAID6+0 can withstand two member disks failure.
• When rebuilding, RAIDn+0 shows greater performance as compared to RAIDn which is undoubtedly better.
• RAID n+0 overhead increases with the number of RAIDn disk groups contrary to RAIDn where the overhead is fixed and does not increase as the number of disks increases.

Thus, RAIDn is more appropriate variant for small (in terms of number of disks) arrays, while RAIDn+0 is ideal for large data storage.