I find it hard to believe the Red SCT ERC value can't be increased from default. As soon as you have a single disk fail in RAID 5, or RAID 1, or two for RAID 6, the remaining drives probably should have higher SCT ERC values set expressly so they do not prematurely produce read errors - which if it happens for sure the array collapses.
The problem with SCT ERC values being "too long" is that controllers didn't have their equivalent error timeout setting to be as long as the disk. So you could have deep recovery for a disk, but then the controller would bail before the disk had conclusively returned correct data OR a read error.
Most people using a NAS probably have software based RAID which will wait for a conclusive response from a drive. So I just don't see the Reds having higher SCT ERC as that big of an advantage for most people who aren't using hardware controllers - OTHER than the fact that the Reds are reasonably priced for the other features and performance they have. Granted, the reduced delay in getting a read error will translate into much faster recovery: even linux software RAID will, on read error, find the data from an alternative source (mirror or reconstructed from parity) and then write that correct data back to the LBA that generated the failed read. That causes the firmware to reallocate that bad sector if it's a persistent write failing sector.
But really, people should be doing scrubs on their arrays. This solves the vast majority of these issues rather than waiting for sectors to get so bad that deep recovery by firmware is even needed in the first place.