I can't help you with how Adidas fits; I don't think I own anything from them.
As for Performance's "house" brand, I have to say that I've returned the handful of things I've bought for their inferior quality, including a pair of knickers. For bottoms at least, I generally find that you get what you pay for. You might check out Campmor.com for a decent price on some PI Sugar Knickers.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher