Ok, so after reading into the drive a bit, it definitely fills a niche and has its purpose. Its performance is mostly on par with Blues and even Black in some cases. After reading into the TLER feature, it makes sense now. When in RAID, like a RAID 5, a normal drive hits a bad sector, it will keep trying to read it, the controller picks up on this long lead time, then declares the drive dead and begins to rebuild that sector. With TLER on the drive, it makes only a few passes, then says the data is corrupt, the controller then rebuilds the sector and everything carries on as per normal, without the drive declared 'dead'. TLER is only on the RE4 drive, but now the Red too.
So, great drive for real RAID (i.e. not RAID 0), not so great for normal system use. The other feature of the drive is its built-in balance mechanism, which allows it to maintain higher performance. The other downside is the higher seek times due to various mechanisms to reduce noise and prolong life.
I'm still iffy over the reduced warranty, but hey, at least I know what it's good for now (not just a price war).