Modpack compatibility

[neuro]

Hey, new here. I was just wondering if it is safe to swap my FTB beta pack A v12 single player world to the mindcrack one. I realize more stuff will be added, but what I'm not certain about is whether or not the additional mods will affect my world. A good example would be my buildcraft and forestry tree farms. I'm not sure if they will suffer from some change in the modpack. Sorry if this is a repost, but please answer soon

 

[ICountFrom0]

that's a tricky, and much discussed topic.
You can use the search to find more on it... but the short answer is "maybe" and the long answer is "don't" and the longest version has dirrections to put your old world regions into a spawned in mystcraft age.
It's always a gamble.