ReadyNAS Duo -- Possible it causes reallocated sectors?

Hi Everyone,

I know that questions about reallocated sectors are fairly common, so I'll try to keep this brief and only include the most critical information about my situation. If I've left any details out that could be helpful to the experts on the forum, please let me know and I'll update my post ASAP.

To start, here are the general specs of my setup:
NAS
- ReadyNAS Duo
- Purchased in March of 2009 from Newegg.com

DRIVES
- 2x Seagate 500GB drives
- Model ST3500320A
- Firmware SD1A
- Configured for X-RAID

Here's a little narrative of the timeline and what has happened. Skip this over and go down to the bullet points if you just want the critical info.

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I bought the two matching 500GB drives separate, but immediately after getting the NAS. Everything installed easily, and the NAS and its drives were problem-free for about two years. In February of 2011, I had my first encounter with one of the drives showing reallocated sectors (disk #1). The count increased slowly at first, so I had little concern. Then, it shot up quickly over a period of a few days, so I RMA'd it to Seagate and replaced it. Not a big deal... certainly, these things happen.

In January of 2012, disk #2 (the older of the two, at this stage) experiences the same, and so I do the same RMA process to replace it. Again, not a huge surprise or problem, easy enough to deal with.

In April of 2012, disk #1 does it over again. At this point I'm finally starting to get a little frustrated, but I know that with electronics, failures happen, and they tend to happen in the relative early days, or late days, so I think, not a big deal, still under warranty. In June of 2012, disk #2 does it over again. Now I'm very frustrated, and based on all the reading I'd done here (and other resources), I direct my frustration toward Seagate. So I initiated the RMA process again, but this time, I did it over the phone. Of course, I was polite, as I know these issues aren't the fault of some CSR. But I stressed that I have now had four disks encounter this problem, and I would like to receive NEWLY MFG. drives this time, instead of refurbished ones. I didn't think this request was unreasonable after four disks, but my expectations weren't crazy. That being said, when I received yet another refurbished drive, I wasn't shocked. I replaced the drive and went about my business.

Now, in the last two weeks, both disk #1 and #2 are having the issue. Disk #1 is up to 15 sectors, and disk #2 is only at 2. I know that the rule of thumb is anything under 50 can be considered somewhat normal. But given my past experiences, I want to be ahead of the curve and I feel confident saying that I know what's coming... necessary replacement on both drives.
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Summary of reallocated sector issues:
- Disk #1 has issue in Feb. 2011
- Disk #2 has issue in Jan. 2012
- Disk #1 (RMA refurbished replacement) has issue in Apr. 2012
- Disk #2 (RMA refurbished replacement) has issue in Jun. 2012
- Disk #1 (second RMA refurbished replacement) has issue in Sept. 2012 -- has not been replaced yet
- Disk #2 (second RMA refurbished replacement) has issue in Oct. 2012 -- has not been replaced yet
- Using an external enclosure, I tested each drive on my old Ubuntu laptop, and Ubuntu shows the same reallocated sector counts

Usage:
- NAS runs from 7:30am - 1am each day, powering down using the build in power scheduling feature (17.5 hrs daily).
- This is home usage. Occasionally, videos may be streamed to my PS3, but the majority of constant use is streaming music while I work during the day. Otherwise, it's mostly there for convenient storage of files that are accessed sporadically.
- Is surge protected, but is NOT on a UPS. Was on a UPS until late summer of 2011. Have experienced fewer than 5 power outages in this time, and the device always has booted back up and checked its sync without problems.
- The unit is on a shelf in my office with plenty of airflow. The drives constantly show in Frontview as being between 95 and 105 F, depending on the season and usage at that moment. I clean the dust off it and the shelf and desk regularly, and check the dust on the fan to make sure it stays clear.

I have had no other issues with the ReadyNAS.

My question is, is it possible that the ReadyNAS Duo could have some issue that causes this reallocated sector problem to be so persistent, across six different drives? If so, how do you recommend I proceed? Is it just time for me to get a new NAS and new disks? Or do I have a legitimate case for Netgear support to replace the unit? Is it just a case of this crummy model of Seagate drive continuing to be crummy (fair enough... only reason I'm not jumping to this conclusion any more is because the one constant here has been the NAS, across SIX failed drives)?

I have loved this unit. It is a great value. I don't in any way blame or have any anger at Netgear, or even Seagate, for that matter. I know these things happen. I just want to know what to do so I can get back to the stability that I should have. It's one thing to have to swap a drive once every year or two. It's another to have to do four in a single year. The length of the drive RMA cycle kind of proves that this is not expected behavior.

Thanks so much in advance for all your expertise.