ICE trikes are wonderful machines, but I'd suggest that two wheels would be a better choice for audax. As with uprights, recumbent trikes work out about 10-15% slower than an equivalent recumbent bike, and while you can climb as slowly as you like (gearing down to the limit of traction), thats more useful for weaker riders and loaded touring than for someone who expects to achieve audax pace.
For audax I think the ideal recumbent is large-wheeled and relatively high up. This will roll efficiently at lower speeds, perform well on crap road surfaces, give you a good view and work well for group riding with uprights.
Small wheels don't react well to potholes, but help shorter riders reach the ground.
Its harder to avoid surface hazards on a trike than a bike. On the other hand it's also a lot harder to fall off if something goes wrong (blowout, ice, diesel etc).
Low recumbents have an aero advantage (not least, being sheltered from sidewind), but you will tend to get splattered in crud by every passing wheel (cycle or motor vehicle) when it's wet.
Trikes have no real learning curve. Bicycles require practice, and may appear hard to control to the inexperienced, even if they're actually quite stable. As a newbie, you'll have no real idea what works best for you in terms of things like mesh vs hardshell seat, suspension options, or the different types of handlebars.
My usual advice is to buy a middle-of-the-road touring bike (something stable and easy to ride) second hand, ride that for a bit on the understanding that it won't be particularly high performance, and then commit n+1 when you've got more recumbent experience and a better idea of what you actually want.
Second the recommendation for a trip to D-Tek - he's hard to beat for the sheer variety of things to test ride.