Then I'd suggest getting help from someone with experience should it become necessary. Adding a header is simple enough, but it's probably better to play with a cheaper board first.
Lots of stuff I've never considered using, so I wouldn't know. Voice? CoS? Who cares? But all the important managed switch features are there. And much more, since you can run anything you want. Well, almost. It's not a very powerful device. After all it's only a switch
As a sidenote: The top image in the Wiki was of the unsupported/unsupportable V2 revision with "ProSafe" branding and a "factory defaults" button on the front right -- the V3 has neither. I fixed that now to prevent mixups.
(Also thanks to @tmomas -- who apparantly doesn't sleep nor rest to keep the Wiki and the Forum in line -- for fixing up some media file shenanigans.)
IMNSHO: For signal wires just treat holes as solder points, add some fresh solder and tag on the wires. That's plenty strong for signal wires as long as you're not using them to hang the device from the ceiling. Going into the holes is really only needed if you want or need to insert header pins.
I bought a Zyxel SG1200-8 port smart switch from Amazon to get access to VLAN100 on the SG108Tv3.
It took a day of playing on the Zyxel SG1200-8 to chart out how to talk to a VLAN on a PVID access port.
I found out that a router loaded with Openwrt could do the same thing, if the router had a cooperating switch built in.
To be safe, like bmork, I soldered in 3 Berg pins into the SG108Tv3; it took an hour, even with the photo from https://openwrt.org/toh/netgear/netgear_gs108t_v3.
I had to scrape off solder flux and check for solder bridges around the dense pcb.
After soldering, I added the wire colors to the table as follows:
I can't remember, so follow bmork's advice and use the initramfs image.
I didn't have to block 220.127.116.11, because I used a 2nd (USB) adaptor set to 192.168.0.32 to the switch at 192.168.0.239 which blocked internet access.
Just to state the (hopefully) obvious, never rely on wire colours - while there are some customary choices around them, they're not standardized and may differ between vendors. Always make sure to confirm the actual allocation before. While you can (and often need to-) switch rx/ tx around, misplacing GND or Vcc can do real damage.
I never use Vcc. GND can be found with an ohmeter. Knowing rx of the USB probe, I swap rx and tx around until I see output, then connect tx to the pcb. The C50v4 refuses to boot if rx and tx are reversed.
Followed the instructions in the wiki and ended up with a soft brick. I then tried to solder a header without having proper de-soldering tools at hand, and messed up one of the holes. Sure, the latter is on me, but the former warrants the warning in the wiki, imo.
This is to encourage others that might be undecided:
I also got myself such a switch now and can confirm that flashing succeeds just via Webinterface and without registration. I attached the switch to just a computer, no DHCP and no access to the Internet for the device.
The serial port was NOT necessary in my case. As always you should be aware that this MIGHT be needed if anything fails, but it is not a hard requirement anymore.