I'm taking Gedarel 20/150 which has 20micrograms of oestrogen- it's considered a low dose in the UK, most pills have closer to 30 or 35 micrograms. I'm struggling to figure out what Microgestin has in from google, but if it's a low dose one, I presume it's a similar amount?
I prefer the lower oestrogen dose as I have big boobs and I didn't want to make them get any bigger! Also there's less breast tenderness on the lower oestrogen, and having massive sore boobies isn't any fun at all
I don't think that it's made any difference to my weight loss in all honesty- I was on a higher dose before I started dieting and never successfully lost any weight, but I think that was more due to my lack of willpower than the pill! The only thing that I have heard as a common side effect of the lower dose is breakthrough bleeding/spotting, which I do occasionally suffer from, as oestrogen controls bleeding, but for me it's only occasional and pretty light and not too much trouble.
Hope that helps!