Get the OV tune. It provides exactly what you are asking about, without any headaches of engine lights, snake oil claims, or daily driver sacrifices. Ive had mine (on 2.5) well over a year, got it after seeing the folks on here running trouble free and mine has been no different. Peppier car, more grunt down low in my case, fun to wring out, no problems.
As for warranty, thats up to you, but one of the things that attracted me to this car was the lack of "major known issues" showing up on the forum, like head gasket with older subarus or major oil consumption on lots of brands. I was willing to take the risk, both of a possible issue, and even then mazda finding out about the tune. Nothing so far leads me to believe its much of a risk with this particular car and tune, have not seen one person have reliability or worse issues post tune.
I just changed my oil at 7k (29k total). Hadnt lost a drop (figuratively speaking) and old oil still looked good. Very happy with this engine and tune.
I saved 1k by opting for the manual, so i put half that towards the OV tune (my justification of course!)
