5 Star gets decent results on their 87 tunes, if I'm not mistaken. I think they have some dyno graphs over on Stage 3s site. Obviously, the price jump to running premium is pretty steep, at least around here (it's usually $0.60/gallon more than 87). On my 36 gallon tank, that's around $15-18 dollars per fill-up depending on how low I take it. Granted I only fill up once every two weeks, but that's roughly $400 a year more in fuel costs (at least right now while gas is cheap).
EDIT: From the Stage 3 site re: 5 Star tunes>
On 5-Star's dyno run with the stock tuning, their test truck managed to hit around 260 horsepower and nearly 350lb-ft of torque to the rear wheels. On their run with a 93 octane performance tune, their truck put down a whopping 315 horsepower and 445lb-ft of torque to the ground. Those are rear-wheel peak power gains of over 20%, all with greatly improved transmission function.
Even 5-Star's 87 octane Performance/Tow tunes make great power, putting down peak numbers of 305 horsepower and 375lb-ft of torque
EDIT 2: So only 10HP, but 70TQ going from 87 tune to 93 tune. Hmmm.....