Depends on your desires. My desire is to have a really fast/quick car, if thats yours too, then go with the Mazda. I like your Yaris, because it's not a " popular" import. You go to a meet, see 19 EVo's, 27 SRT-4's, 10 STI's, 2 million Honda's, & 7 Mutangs.lol
So, stay you. I'm wrestling with same problem on my Celica. Trade it for faster car, or finish it, & say f-it. I'm saying F-it, I'd rather be at a meet & be 1 of 2 other Celica's there, than to be just another import/popular Neon.( no offense to anyone).
Boost the Yaris with the extra $150 you'll save, & be unique. My

....Vegeta