If you are not happy with this desktop RAID that is not a true hardware RAID type that does not have the bells and whistles of a fully hardware RAID solution I think it might be best to look at another RAID solution that is to your needs.
You say verify and rebuilds these are two different things:
verify will degrade performance a bit but cancelling it will not it will only not repair the array.
rebuild is when a disk has failed performance will be degraded if you don't run it or run it with a replaced disk.
So why is this desktop RAID solution so limited and not a true hardware RAID you ask....it has a chip therefore its hardware...well no...the chip doesn’t have a CPU to run the RAID...where does the chip get a CPU from..your main CPU...how is the chip linked to your main CPU...so its a software raid with hardware that is mainly so you can boot off from.
Now why so limited if desktop RAID had it all no one will buy these fully hardware RAID card solutions...but one day desktop RAID may have these features.