An interesting note on the 2.3l. You don't notice it from the cab of the Ranger much, but the DI injectors are Noisy!!!!
Hang on here... let's just agree that no matter what there are some of us who will always want to add HP if it's available. Correct me if I'm wrong, but if the 2.7 is also turbocharged I'm going to guess that anyone tempted by a tune on the 2.3L would also be tempted by a tune on the 2.7L, too. And since the 2.7L is also an automatic only I'm going to guess (without reading about it because that would take the mystery out of it for me) that any 2.7L tune would be for the engine only and a separate tune would be appropriate for the transmission. So, if you are the kind of person who always will want a bit more, it's far less expensive to start out with the least amount of money out of pocket so your baseline is far lower. Because come on... if you are debating about a tuned 2.3L because you are tempted by more power you KNOW you will be tempted by the 2.7L tune(s) that will be available.Since you mention you could go with the 2.7, it seems that you are getting the automatic transmission either way. So the only extra cost for the 2.7 would be the $1800.
At $800 (with tax and shipping, lets call it $850 to make it easy to compare), you are almost half way to the 2.7. After the tune, you are forced into 91 or higher Octane. Average miles per year 17000, combined mileage probably around 17 MPG mixed, so 1000 gallons of fuel.
Nationally $0.55 higher prices for premium vs. 87 (which the 2.7 will happily run on), means an extra $550 a year on fuel for the tuned 2.3. After a year and a half, you are even on money and still have the 2.3 instead of the 2.7. Even if the 2.7 gets worse mileage by 20% (and it won't) you would be even before 2 years was up. So after two years, your tuned 2.3 (which is making less power then the 2.7 on regular fuel) is costing you more in total (initial cost plus tune, plus operating costs) and it gets worse every mile you drive.
It gets worse if you sell it actually, as you will recoup some of the 2.7 costs there over 2.3.
I suppose for a very few people who are going to sell within a year, or for those forced into the 2.3 (manual folks), a tune would make sense, but for the majority, not so much.