All wired direct to the battery, in my case
 

I've skim read the instructions on their webpage: you are expected to wire in the yellow wire to negate the possibility of completely discharging the battery.

Your new equipment could be wired directly to the battery - mine is, via a two wire connection. Yours has a built in fuse so there is no need for a separate one.
As I mentioned in my earlier post, mine has a built in switch - you could choose to add a simple, separate switch and forget about the yellow wire (then you just have to remember to switch it off when not using the bike).
I have left mine on for a while - can't remember for how long - and it draws very little current in any case. In other words it would take an "age" for this kind of kit to discharge a bike battery.
On the other hand, I don't leave a phone and the like charging on my 1/2.1 Amp dual USB connection unless the engine is running.

For me, I choose a voltmeter which shows actual voltage.

Fit it through a relay, together with your other accessories. This way, no power will be drawn when the bike is of. Some USB chargers have a slight poweruse, even when theyre not in use, when ired "hot" all the time.

I chose the same type of voltmeter i.e. with the digital display of actual voltage.
However, I chose one to wire it directly to the battery so I can switch it on to see the battery voltage reading without inserting the bike key.

Certainly, it does require me to pay an amount of attention to switching the thing off when I don't want the read out - as you say, the "USB transformer" from 12V to 5V draws a very small amount of power when it is activated.

Jens, what is the use of installing a relay too if the voltage monitor is installed to a switched live feed? Isn't that accomplishing the same thing using the key / ignition?

Thanks a bunch :)

I've been going thru my bikes and installing volt meters . Have picked up several styles to see which one I like the best , one has those multi color LED in a line to show state of charge . I'm hooking mine up with the red wire coming directly from the battery hoping to minimize voltage drop from tapping into another circuit at fair distance already from the battery . I then hooked the ground wire to my right hand kill switch (I don't have most hooked up to the ignition anyways ), just have to hit the switch when shutting down and starting up , not sure if I want to do them all that way or not yet .

Otherwise will hook one up to a mini relay that's signaled from the red ignition wire coming out of the key switch , the relay is for accessory lights and see how close it'll read off that compared to right at the battery .

Yeb, that would be two of the same thing. But i feel "tappin in" on the bikes wireharness is a messy solution. I have a relay and use only switched live feed to trigger the relay. I also have other stuff fitted to the relay, 12v output, and heated grips.

An added benefit of wiring the voltagemeter throug a relay, is that the voltage it meassures is straight at the battery, and not through other drains and through the ignitionlock, switches ect.