Equallogic PS6210x Convert RAID 10 to RAID 6

I know this is supported but my question is what impact should be expected when a RAID 10 configuration gets change to RAID 6.  I also already know that once that change is made I cannot go back to RAID 10 without 1st wiping the RAID 6.  I understand it can take quite a long time (any numbers regarding time estimates would be very helpful) but I don't know if there is an outage involved, is there significant performance degradation that I need to be aware of, etc.  I am configuring the new array as RAID 10 which is eating up tons of my available storage with the backup plan to convert to RAID 6 (unlikely) in the future if we run into significant unexpected data growth.  I may decide to just go with RAID 6 if the conversion later is going to have a significant impact on the business.  I really need the performance of RAID 10 but need to understand the impact of converting in the future if I need to.  Any help that anyone could offer would be appreciated.