Help with migrating/transfering SL to ML between computers

Howdy,

Forgive me if I'm asking something that's been asked a billion times (or if I've posted in the wrong forum), but I've tried searching and came across either confusing instructions or ones that didn't quite apply to me.

I'm looking to transfer a lot of folders/files, as well as preferences (Firefox, Safari), Mail accounts and prefs, and likely a couple of apps too. I would be transferring the files from a 2009 Mini running Snow Leopard to a 2012 iMac running Mountain Lion that is ALREADY set up with many apps installed. I have Time Machine backups of the Mini in an external HD.

A lot of what I've read around the web seems to be for when migrating on initial set up of a new computer with the MA, and a few people even emphasized that the migration should be done only then. However, that's impossible for me as the iMac is already set up and there are already apps installed, etc. and it's not viable for me to redo the entire thing. Besides, I'm really not looking to do a complete migration. I'd just like to move some (a lot of) things over.

I'm hesitant to plug in my Time Machine HD at the moment, because I've heard horror stories about people's entire backup being wiped clean upon using it for ML. So I guess my question is kind of two-part. Is there something I need to watch out for in regards to Time Machine and how it behaves when switching over to ML from SL on a different computer? And what would be the best way to go about transferring the files/prefs/apps I need to from the backup?

Any help would be greatly appreciated, thanks!

 

I have the iMac set up with a different external HD for Time Machine (backed up from scratch), but admittedly, I haven't given it much thought yet as I was mainly focused on getting everything moved and set up properly before I start backing up regularly again.

Perhaps I should add that the Mini will be kept around as a computer I'll be using for testing, some apps, and for the SL. I plan to eventually hook it up to the iMac (screen sharing, I think is what it's called?), however my main computer will be the iMac and I need some files/prefs/apps moved over. Both computers will still be used beyond this point, just set up differently for different purposes, hence different Time Machine backups. I had chosen a separate HD because of the aforementioned horror stories about backups getting wiped out.

I'm not concerned with having backups dated back years and such. All I really need is the latest backup of the Mini, as once both the iMac and Mini are set up the way they'll be used in the future, the backup will be the only true backup I have of the way things were "originally" set up prior to splitting my files and apps between two computers.

I hope this makes sense...

I have several concerns with using the MA, mainly because I was told that it ends up migrating a lot of files from SL that can't be used on ML so it just creates clutter - which is something I'd like to avoid. I'm also not sure "Inherit Backup History" is suitable (if I'm correctly understanding what it is). Will that be more for people who do complete migrations and setting up through it?