My current disk array that contains my footage consists of three 1 terabyte WD Black drives in AID0. When the disks are empty, their read and write speeds are around 350 megabytes a second.
In the meantime, I'm interested in moving from editing compressed 1280x720 footage (compressed with the Fraps codec, usually around 15-25 mb/s), to editing uncompressed, 8-bit 4:2:2 YUV at 1080p30, or 1080i60, or perhaps 720p60. The source of the new footage will be a Blackmagic Intensity Pro, capturing PC game footage. The bitrate of my new footage will be around 100 to 125 megabytes a second. Will my current array be fast enough to feed that source footage out and allow me to scrub through it, etc... or will my array be a big bottleneck? I'm not sure if a 3 to 1 ratio of array speed to video bitrate is going to be great enough to sustain smooth playback in Premiere.
The TLER issue shouldn't affect software RAID.
Your setup looks good: at nearly full, the array will slow down to about 50% of the "fresh" speed - i.e. around 175MB/s, which is still enough to support a single stream playback.
(A 20% headroom is generally a good number to support smooth playback, i.e. the drives should be about 20% faster than the video bandwidth.)