First off, congratulations on the birth of your daughter!!
I used to use Dr. Brown's, still love them. My DD had colic, gas issues, still is quite the spitter, and those bottles were great. I am now trying the Born Free glass bottles, but they only make them in wide-neck version and my DD isn't used to the wide-neck nipples. She is a bit gassier on these simply because the nipple is so much bigger, and she doesn't "latch" the same way. But I'm continuing to try them. I really like the glass actually, didn't think I would.
Anyway, the heating. When I first brought my DD home, I was heating water in a cup in the microwave and putting the bottle in that warmed cup of water to warm the formula. But that was taking awhile, so then I bought a bottle warmer and loved it (now we have 2 of them, one for the nursery and one in the kitchen). So that's what we've used ever since.
As far as worrying about the heating issue, evidently it just doesn't matter HOW you heat the polycarbonate plastic, just that it's heated at all, that's what causes the chemicals to leach out of the plastic (so ANY method of heating it can release the chemicals). I guess even if you use the plastic after being in the dishwasher, this also can be a problem. However, some scientists feel the amount of chemicals released is not significant enough to worry. Others feel it's very significant. California just banned phthalates in plastics there. I would suggest research as much as you can before you make your own
decision. I won't try to persuade you one way or the other.
Do you use wide-neck Dr. Brown's or standard? If you are thinking of switching, and if you use wide-neck, I bet you'd like the Born Free bottles (either glass or "safe" plastic), because they are also a vented type bottle. But they are pricey. I really like them, but as I said my DD doesn't really like the wide nipple--we'll see what happens. But also, Dr. Brown's is coming out with a glass version in December, and a "safe" plastic in Spring 2008, if you want to wait to switch. There are other alternatives too. There are Evenflo glass bottles in standard, but they are not truly vented. Also there are both wide and standard "safe" plastic through Green To Grow bottles, but they are also not vented. Playtex Drop-ins and Avent Tempo (drop-in type) are also "safe" but again not vented. Gerber Gentle flow is another, unsure if truly vented or not. But I share your concern, because my DD had a heck of a time with gas and spitting up and has acid reflux. Good luck making your decision!