The hub came with a 16T cog. I was thinking of ordering the Thorn 19T cog with the frame and going 43-19 with gearing instead of 38-16.
What are your opinions on increased drivetrain life with the bigger cogs? Would the increase be dramatic?
The initial cost could be partially recovered if someone on the forum wants a half price 16T cog 
There's a reason Herr Rohloff fits the 16T sprocket as standard: it's very versatile, and the longest-lasting of all his sprockets.
I'd like to see you get the 40% longer chain life that Jim postulates, but I won't be betting my own money on it. For a start, with an uneven number of teeth, you're already excluding yourself from the minimum wear characteristic of an even-tooth count. Personally, I think that the wear characteristic of the odd-tooth count of 43x19 will cancel out the size advantage over the even-tooth count of 38x16, and you'll end up with no advantage for the additional expense. (Basically, this is because the inner plates of a chain are always spaced at 1/2in exactly, with all the wear concentrated in the outer plates, so if you always put an even-tooth count chain back on in phase, or never need to take it off, for which see below, only every second tooth wears, and a chain with an even number of teeth lasts longer.)
It thus seems to me that you're going the long, expensive, inconvenient way about a simple problem of extending cog life. The life of the Rohloff sprocket is already extraordinary. Good quality chainrings, like Thorn's own thick ali ones, or the stainless steel Surly that has a vogue on this forum, also already last very well. Good quality chains like the KMC X8, also popular here, have a track record of lasting extremely well and being cheap as dirt at least at the discounters.
Your choice of 43x19 offers gear ratios practically identical to 38x16. The difference is that with 38x16 you already own half the components, so that is one purchase price and carriage charge you can avoid. The choice of 43x19, besides being inherently faster-wearing than even tooth counts, also excludes you from the top strategy for increasing transmission life:
The key to a long transmission life is to keep dirt out of it altogether.
The key to keeping dirt out of your transmission is the Hebie Chainglider. The Chainglider fits 38, 42, and 44 tooth chainrings, and all the standard Rohloff sprockets. I doubt it will fit the non-standard 19T Thorn sprocket, but you can ask them. It doesn't fit the Thorn chainring too well (the chainring is too thick), but there are some working installations here with the Thorn chainring and the owners haven't reported noticeably sub-optimal operation. Your suggested 43x19 drive won't fit a Chainglider. (And there aren't any good alternatives to the Chainglider. I tested them all. Search for my report on this forum.)
In summary, 43x19 cogs aren't likely to increase component life (over a 38z16 choice); such a choice is in fact an unnecessarily expensive way of failing to achieve an unnecessary aim, and excludes you from the much more convenient way of achieving the same aim, and some others more desirable, like minimum or zero chain maintenance. (Yes, that's right, zero chain maintenance; I have an ongoing experiment of running a KMC X8 chain inside a Hebie Chainglider with only the factory lube, currently at 2600km; description elsewhere on this forum.)
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A note about "unnecessary aim". There are some champion chain-life extenders on this board, absolutely amazing mileages. The optimum Rohloff touring transmission setup for longevity seems to be 16T Rohloff sprocket, 38T Surly stainless steel chainring, KMC X8-9x chain, and Hebie Chainglider. But note that for most of us with this setup the primary point is maintenance reduction, because even open this combo gets really good mileage. Though I'm a big booster of the Chainglider, I reckon you'd need to be a constant commuter, say 10K a year, or a world circumnavigator, to recover the cost of the Hebie (mine was under 60 euro landed) in extended transmission life, simply because the components we're typically enclosing already have such excellent life. So I view the Chainglider as a luxury/convenience item.
