I am not an expert, but I made the change you are talking about on my last bike, with not a lot of work, according to DH. My new (not so new now) Trek came with a compact/11/32, which I really like, but is missing the 15 cog, I was always in, on my triple. I got used to it, but I change gears a lot more. My custom Guru was bought before they had lower gears for road bikes. I have a long cage, mountain bike derailleur with an 11/34 on my compact double.
I am hoping to upgrade my Trek to the 34 in the next year or 2.