A fundamental problem with these analyses is the underlying question of what is an acceptable "ROI" on your advertising/marketing spend. The article says "We believe 200 – 300% ROI is very reasonable to expect. This is doubling or tripling the money you invested with bookings." But their figure is ridiculous! Most guidance I've seen for small businesses (in general, not necessarily hospitality specific) suggests that businesses (that are going concerns, not start-ups) should budget between 5 to 10% of expected revenue towards marketing -- this implies you should be looking for an "ROI" of 10X to 20X on your ad spend, not 3X!
Another way to think about this is to figure out what the "effective commission" rate is that you would be paying. If your ROI is only 2X to 3X on your TA business listing, then you are paying TA an "effective commission" rate of 33% to 50%! In those terms, B.C at 15% commission is a much better deal! (That's a 6.7X ROI).
Remember that you have a lot of other costs beyond just your advertising -- you need to make sure that the business you are bringing in is helping to pay all of those costs, not just covering your ad spend...
The other problem with these analyses is one that HJ has pointed out -- the assumption that the rooms would remain vacant if it weren't for TA (or whatever other ad medium you are considering). So when considering investing in a "new" ad spend in addition to your existing marketing, one has to look at how will the new ad fill in your existing vacancies (slow periods, shoulder seasons, etc...) -- getting bookings from the new ad for the times that you would already be full don't count! If it is a renewal, you have to give consideration to how your other marketing would fill in any gaps left by dropping TA (or any of your other advertisments).
In case you can't tell, I am generally pretty skeptical of the claims about ROI that I can expect made by places that are vying for a piece of my limited marketing dollars....