The Gen1 with a decent power supply did work very well albeit rather slow. The Gen3 or Gen4 models are about 50% faster disk transfer speeds and vastly better wireless. The Gen5 has the same disk speed as Gen4 and didn't really gain anything.. the wireless does gain AC wireless but you need new clients to take advantage of it.. and that means close in.. 5ghz AC high speed is for same room or next room speed improvement.
The Gen5 is rather more delicate .. removing and installing the hard disk is a project to be undertaken with a fair degree of skill. People tear the ribbon cable that is not replaceable. It is also breaking warranty on a box that has not proven to be over reliable and hence you may well need to exercise warranty.
At over two years old now it is well past replacement.. so buying the current model I don't think is a good buy..
3. Attach an external 4/5TB HD to the Time Capsule or Airport Extreme (this is a newer "tower" model w dual band running in bridge to enlarge existing same network) and point backups to this usb attached HD
The time capsule is used for backing up my primary machine. We also have an iMac we use occasionally that I'd like to back up to the same drive (another partition?) if possible...
I think buying an Airport Extreme and use it with a USB drive is not a bad idea. It means if the unit breaks down the backups are safe. You don't have to open the unit to pull out the drive. Over wireless the USB drive is not going to slow things down much.. over ethernet I have to say it will make backups a lot slower. You do need to buy the RIGHT USB drive.. some are not reliable.. they work for a day and then start having spin up issues.
I think myself.. I would toss up between buying a Gen3 TC (or Gen4 which has better wireless but somewhat less reliable). And put your big disk in it. You can also plug a USB into it.. simply rotate your current 2TB.. archive it and then erase and keep using it.
Or as above .. buy the AE (AC model which is Gen6) with USB drive.
OR if you have a need outlay the money on something better.. This is a more expensive way but buy a QNAP or Synology NAS.. load it with a couple of WD red drives. They are not wireless.. so you need a wireless router to plug it into.. although I am guessing you are using ethernet as the Gen1 wireless is hardly tremendous. As I said it is not cheap solution.. but it is a solid hardware solution and you can certainly improve your network backup speeds to full gigabit transfers. (best case scenario admittedly)
The cheapest way to do this with an iMac in the network is to buy a large USB drive.. plug it into the iMac.. (USB3 is ideal.. if the Mac is older than 2012 it only has USB2 ports but you have thunderbolt for 2011 and FW800 which are still available and faster than USB2).
Simply partition this drive and make it available to the network .. you can do TM backups over networks.. and USB2 plugged directly into a Mac is still faster than network backup to a TC. At least one computer then backs up over local drive.. much more reliable that way.
