SWTOR patch 1.3 has hit the test servers, bringing a new round of various legacy bonuses. The numbers may change in testing, but they did get me thinking about how some things that sound good on paper don't work out so well.
I did a fair amount of math, summarized below, trying to figure out if the companion gift affection bonus was ever worth purchasing. The answer is extremely borderline, because the bonus is per-character, there is a limited amount of affection you can earn on each character, and the only way to "cash in" the bonus is to consume a gift that has a cash value. In order to profit from a 5% affection bonus that costs 25K credits to unlock, you need to be spending over 100K credits per companion for each of your five companions. This is technically possible if you intend to powergrind each companion from 0-10,000 as quickly as possible using vendor gifts and paying whatever it costs on the trade network. Most people probably will not do this.
I got sufficiently into the analysis of this that I lost sight of the bigger picture. There are two additional ranks and these boost the costs even further - a total of 250K credits for the top rank. It's also worth noting that the two perks for conversation gains and gift gains are somewhat mutually diminishing in value - due to the cap, the more affection you gain from one of the two, the less remaining affection there is to gain from the other. (The conversation option has the advantage that players will do this anyway - you still have to earn more affection than you could buy with the credits for this to be worthwhile, but at least you don't have to be planning to spend an unreasonable total amount on gifts to profit from it.)
Don't get me wrong, some of the new legacy unlocks are legitimate luxury item credit sinks. These particular bonuses, though, especially for the top two ranks, are never worth the money for anyone. As with your real money, I suppose the lesson is "buyer beware".
The numbers
The chart below summarizes the cost of power-grinding the 80% of companions who have at least one gift they "love" for maximum favor using vendor gifts. You can get from 0-8000 affection for under 100K credits using gifts from the vendor - which means that the 5% bonus you paid 25K credits for saves you fewer than 5K credits per companion. If your crewskills and/or the auction house are more cost-effective than the vendor - or if you are less excessive in your use of gifts, you will save even less.
| Affection Range | Affection/Gift | Total Gifts |
| 0-1999 (base) | 96 | 21 (to 2016) |
| 0-1999 (+5%) | 100.8 | 20 (to 2016) |
| 2000-3999 (base) | 48 | 42 (from 2016 to 4032) |
| 2000-3999 (+5%) | 50.4 | 40 (from 2016 to 4032) |
| 4000-5999 (base) | 19 | 104 (from 4032 to 6008) |
| 4000-5999 (+5%) | 19.95 | 99 (from 4032 to 6007.5) |
| 6000-7999 (base - rank 2 gifts) | 19 | 105 (from 6008 to 8003) |
| 6000-7999 (+5% - rank 2 gifts) | 19.95 | 100 (from 6008 to 8001.55) |
Total Rank 1 cost saved: 8 rank one green gifts (1600 credits) per companion, 8000 credits for five companions (assuming none who are picky)
Total Rank 2 cost saved: 5 rank two green gifts (3000 credits) per companion, 15000 credits for five companions (assuming none who are picky)
Total "saved": 23000 credits
Total Spent to earn these savings: 25,000 credits.