what type of storage are you using? if sun recommend you to use it, it will have a reason, what did you ask them?

a raid 1+0 is for sure the best way to build a high availability "disk" and the fastest, but to be honest with you, the most of my costumers don't use it, because it is the most expansive way, too. it costs exactly the double money of your space.... you lose 50% of your disks.... with 4 disks it doesn't matter, but think about 2TB luns so if you make a raid 5 with 10 disks, you would only lose 1 (10%), 20 disks 1 (5%), and so on and so on...
at the end of the day, it's a performance question, if you have to handle a raid 5 without a HW-controller and without HW-cache the performance is extremely bad and it costs CPU power...

i would also recommend you to use a 1+0, but it belongs to you. do you want to spend more money, speed it up and get a better availability... or save money and get more space on performance costs...

regards PRESSY