Anybody having problems with Evenflo Elan line bottles? If so, what kind and what are you doing about it?

I've started transitioning my daughter to the bottle in preparation for my return to work. I bought several of the Evenflo Elan line bottles - I like the variety of colors (keeps me straight on my breastmilk freshness) and I like the wide mouth bottles (shaped more like my breasts). But I've been having some troubles. First, the bottom screws on, and I've noticed some leaking from where it screws on. I've been really screwing it on tight. Then when I warmed the bottle in a bottle warmer (one of those that you add a little water to, and the burner heats the water up and warms the bottle), the milk is not getting warm enough based on the guidelines provided by the bottle warmer. So I'm using way more water than the instructions say. I have a feeling it's because of this screw on bottom. And then last night, in the warmer, the bottom completely popped off - all the milk leaked out of the bottle and into the warmer! What a mess. Anybody else having these troubles?