Well, the net benefit of the t730 is that:
a) It's pretty small (4 Liter chassis compared to the 6 Liter dimension f the HP EliteDesk USFF models, and 13 of the usual SFF)
b) It's very quiet (one chassis fan with a single heatsink)
c) It has quad DisplayPort output (which means that after you upgrade to a newer device, its still a decent machine with AMD Netfinity support for multiscreen gaming or as an HTPC) - remind me to do a video on its gaming capabilities for an STH "After-Hours" thread.
d) There is also native support for a Broadcom BCM5709 Fiber GigE card that hangs off the M.2 slot and uses an SC connector - and that one can be obtained very inexpensively ($13).
e) It has a PCIe x16 slot (really an x8) so you can put a quadport GigE or dualport 10GbE inside - although a few of us have Mellanox 40GbE/Infiniband cards setup for it. I have SolarFlares in mine,
@arglebargle have Mellanox in his - and I think
@BLinux uses his with an Intel T350-T4 quadport card. Most NUC chassis do not have PCIe x8/x16 ports - and you'll be lucky to have a breakout for a PCIe x1 (probably some Frankensteinean setup and at most it'll be playing with a Realtek or Intel i217 card).
f) It's fairly capable (picture a Haswell NUC or a Playstation 4 with more CPU cores but half the GPU cores)
Frankly, undervolting is a bit of a dead horse to beat upon in this case, since it's already fairly efficient given what you have, which is an AMD Kaveri APcan U, not a Pentium-D like power hungry CPU and can exist in low draw applications, but it's certainly no Broadwell-U or Y - you might be able to tweak it using your typical AMD Zen or Carrizo MSR adjustment tools, but that's unknown territory here.
I don't mess with mine since it's used as an ESXi hypervisor, and I don't think
@arglebargle messes with it in Proxmox or BYHVE when he was doing SRIOV testing.
@BLinux mentioned that he tested the t730 initially at 22 Watts, but once the displays are disconnected and the embedded Radeon R7 GPU shuts down, it goes back to about 11-13 Watts.
@arglebargle also mentioned that you can push the system fan RPMs to a higher setting to wick away excess heat from an external card (which usually consumes 9 to 17 watts depending on what kind of card it is). Not my preferred method - the Gigabyte i7-5775R NUC that I have actually spins up quite often to make it extremely annoying as-is. If you are looking for something that can take an external PCIe card, you'll probably want to look at an HP t620 Plus thin client - slower but more power sipping APU (GX-420CA which loads at 10w max), native AES-NI suppport, and probably even cheaper than the t730.
@Patrick did a video on it - maybe he'll do something cool with Part 2?