Time Capsule vs. Airport Extreme w/ HD vs NAS

It looks like I'm having trouble with my current Time Machine drive and will need to replace it.

I'm considering several options.

I mainly use Time Machine with a FireWire 800 drive for quick backup of my iMac. I'm pretty lax about backing up my MacBook, though--months going by before I remember to attach it to a different drive to back it up, too. So, I've been considering a network solution; the dying Time Machine drive is sort of the kick I needed to go ahead.

Obviously, a Time Capsule is a quick and easy solution to it all. However, one concern is that, as with other multipurpose devices, is that if one part dies, that pretty much kills the second part--i.e., if the hard drive fails, then I must (potentially) replace the whole unit (from what I've heard, replacing the drive in a Time Capsule isn't for the faint of heart).

Then there's an Airport Extreme; from what I understand, you can attach a USB drive to the newest models for use as a Time Machine backup:
http://tidbits.com/e/14347
Of course, that's USB 2, which'll be on the slow side as compared to FW 800, but there's the benefit that if I need to restore, I can detach the drive from the AE and hook it up straight to the Mac, which should be quicker than a wifi restore (for the MacBook; I'd have the iMac hooked via Ethernet).

But there's the consideration that I have a FiOS router, so I don't really NEED another one; I don't think the Time Capsule or Airport really gives me much more than the FiOS router does, and I'd still need the Verizon router attached anyway for other services.

So, the last choice is an NAS drive. It might not play as well as a TM drive, as Apple did take some pains to support their own hardware... are there NAS drives that work better as Time Machine drives than others?

So, the essential question is, what would make the best Time Machine backup, if I want to back up two Macs (one by wifi)?

 

Thanks for the replies.
balamw: did you migrate to the NAS because of the AE/TC speeds, or something else (e.g., more complete network capability)? You mentioned something about a "repaired" Time Capsule... what went wrong? Was it one of the new models?

 

I ended up going with a Western Digital MyCloud drive (NAS). In the end, I decided that the Airport/Time Capsule routes had too much redundancy and not enough additional features, considering that my FiOS router otherwise works just fine. I don't really use wifi at home much at all, certainly not for anything that has much bandwidth--my iMac is hooked up via gigabit Ethernet, and when I use wifi on my MacBook its pretty much away from home.

Thanks for the input.