H310 Mono Mini - Raid Reconfiguration

[toluun]

I just bought an R720 and am currently looking into my options for raid configurations. I am mainly trying to decide between running the card in non-raid mode and using something like unRaid or creating a raid 10 array. The main thing I like about unraid is that is allows you to easily expand your pool. However I've been looking into the raid card(H310) that came in the r720 and it appears the card allows you to add drives without data loss by using the reconfiguration utility. Does anyone know how this reconfiguration works? Is the probability of losing you entire array during this reconfiguration high? Does it put as much strain on the drives as say rebuilding the array due to a drive failure?