If you're not having any problems with the migration (save for the account info, which you apparently fixed) I'd just leave things as is. I'm sure that you knew that non of your PPC-only apps would work with your new machine, so I'm assuming that you've either trashed or updated them?
No physical media for OS X has been shipped since Lion once shipped on a flash drive. Apple just relies on you to maintain Internet access if you need to erase/reinstall Mountain Lion. You should be able to download the "Install OS Mountain Lion.app" from the App Store for free. Once it completes the download, it will open to begin installation. Quit the installer and you'll find the file in your Applications folder. Then you can use Lion DiskMaker (also works with Mountain Lion) to make a USB thumb drive 'recovery' drive and/or a dual-layer DVD (but I'm assuming that you don't have an optical drive - you'll just need a 8GB+ USB thumb drive or two).
As for backup - I use two schemes; I have two Time Machine 2TB external drives and three clone drives in USB enclosures. I maintain one clone as a 'release' clone and use the other two for testing new OS X software releases. With 5 backups in place, it's unlikely that all would fail at the same time. I do use Carbon Copy Cloner and, for me, it's worth every penny of the $40 that I paid. I use it daily and it provides a great deal of assurance that I'll lose very little, if any, data at any one time.
No I still have the two seperate accounts, I just had to rename the login u/n of the one being migrated to something slighty different.
It's actually a Intel Mini (Core Duo), one of the 1st Intel Macs, there was the Core Solo series before that though IIRC.
I'm just thinking I don't even use 1/5 of the apps (guesstimate) I currently have installed, plus I dont like the thought of all the associated crud, if Im going to start from a clean slate, now's the time to do it.
Granted there's probably still a few apps I do use regularly, that I'd have to go through the pain of manually installing & setting-up again, just haven't quantifed that yet, may not be as bad as I guesstimate.
Rest of the stuff is just docs/vids/music/thunderbird/firefox/desktop etc. that can be manually copied accross...
Oh that's right, they offered OSX on a usb-flash at one point didn't they, can we still get that from them?
Does that Disk Maker put together something on USB-flash that's exactly the same as physcial volumes we used to get?
Some more questions on your last paragraph later maybe....
If you want, I think it's best to start with a 'clean slate' so if you don't mind going through the Internet Recovery method (hold down teh Command, option and R keys whilst booting) that may be best. Then install the applications that you actually use and just transfer over you documents. Pretty simple and not a bad idea on a new machine.
No, Apple stopped selling the Lion USB thumb drive and never sold Mountain Lion on any type of media. Lion DiskMaker puts together a Mountain Lion reinstallation disk - pretty much like we had in the 'old' days!
Good luck with your clean machine - might take some time to get everything where you want it but it will likely be worth the effort.
Good luck, again,