Suzie,
Here are my thoughts on pine bark in your situation. I can buy it here for $5 for a 2 cubic bag, which I still consider expensive. On the other hand, I have many dozens of fig trees, so it adds up. These are the attributes of pine bark that are sought after and the reason people (myself included) use it in their mix:
1. Well draining. You can water and water and water and you won't get any perched water table at the bottom, because the particle size is large enough to allow the water to drain out. This is important if you get a lot of rain. However, if you're in new mexico, I doubt that is a concern for you.
2. Takes a couple years to break down, but "Uses" less nitrogen then hardwood mulch or bark. The organisms that break down hardwood use a large amount of nitrogen in the process, rendering it unavailable to a growing plant. This is why it's good mulch, not so great in large quantities in potting soil. Pine bark breaks down somewhat more slowly due to a higher lignin content, so there's more nitrogen available for the plants. You may still need to add liquid fertilizer, depending on how well aged the pine bark is. Mine is not aged or composted at all, so I use a liquid fertilizer every couple weeks or so. I get enough rain that any excess salt will be washed out, so I don't run any risk of over-fertilization.
3. Since it's organic, eventually it will provide nutrients/minerals for the plants. This will take awhile since breakdown is slow, but is one differentiator from a mineral ("gritty") mix. A mineral mix will never break down, but you will have to add all required nutrients in liquid form on a regular basis.
4. Cheap, compared to some of the alternatives. This one obviously doesn't apply in your case.
The drawbacks are often a low pH, which needs to be addressed, and the frequent watering required.
In your dry climate, I would probably use one of the other mixes, since they will hold more water. If you go out of town for even a few days in the summer, your fig tree might shrivel up. But if you only have one tree, you could probably put a bunch of those drip watering things in it, and you'd be OK.
If you are going to use it, make sure you adjust pH if necessary. I've never had much luck doing this scientifically, as I have trouble reading pH tests or meters, and don't trust them. So I just add some lime and hope it's enough. Some people say the pH of the water is more important than that of the soil, whatever that means. Doesn't make much sense to me, since pH is defined as the acidity of an aqueous solution. Presumably, the question is, what is the ph of the solution of water that is saturated in the soil or mix. So even if you add lime, and it temporarily counteracts the acidity of the bark, what happens after the lime washes out? Then you're back to where you were. OK, I digress, but that's what I think about when I think about pH. And if you use anything other than a commercial mix, you should at least think about the pH. Presumably in a commercial mix, a well paid chemist has already done the science and you get something that's right for most plants, which should be between 6 and 7. What happens after 6 months in a commercial mix after the additives have washed out? I also wonder about that. They want to sell more product, so they have an incentive for the plants to grow well for a period and then stop growing well, thereby creating demand. OK, now I really digress.
In summary, if you use the pine bark, make sure you water enough, and watch your pH. Good luck.