More a note for others that might be searching for HDD upgrade options for their UCK-G2-PLUS.

Getting larger 2.5" HDDs is generally expensive & difficult in NZ, but external drives are cheap & plentiful. The issue is knowing what's inside them...Western Digital for example often have the USB port on the drive itself. It can be hard to find info online. 

Of course it would be nice to put a proper 'DVR' drive in, but they are again very hard to track down & expensive in 2.5". Ubiquiti just ship a bog standard 5400RPM 1TB HDD anyway (the last few I've seen have been Toshiba). 

The 4TB Seagate Expansion Drive STKM4000400 has the ST4000LM024 HDD in it - to buy the drive on it's own is about $150 more (nearly double the cost) of buying the external & removing the drive. Of course there is no warranty in this case, although those enclosures are pretty easy to open & remove the drive without damaging them, it's very hard to remove all the metal tape stuff off the drive without ripping it, but you only get a 2 year warranty with the standalone drive anyway (vs a 3 year with the external drive....? why?) so the chance of ending up worse off is very slim. 

Hope that might be helpful for someone.