This was a replacement purchase but with the intention of using the Time Capsule as a server as well as backup unit.
The Time Capsule works brilliantly as a back up unit in an Apple Mac environment, however the life span of Time Capsules has been problematic: early TC life spans were circa 18 months; my previous TC lasted 3.5 years. In choosing to stay with a Time Capsule, my expectation is that Apple has improved the design of the power supply which was causing premature failure. Time will tell.
I chose a 3TB unit with the intention of using it to also backup more than my Macs. Annoyingly, it is not possible to partition the drive: Time Machine wants to make use of the whole of the TC capacity (ie all 3TB). This rather defeats the benefit of the larger capacity drive (1TB is more than adequate for backing up my Macs).
I have identified work-around to limit the size of the "sparse bundle" the TM uses to store back ups which should achieve the same effect as partitioning. However I have not had the opportunity to test it.