I would not trust anything that say's "it's Garage Band for windows " ... but hey that's just me
In any event , I love GB and I can tell you that very few "GB users only " know how to get the most out of it ...
A lot of GB users think that they have to export full mix's and they do not know that in GB you can have a 20 + track projects , even twice that and have each track as a separate render of the track to use in another DAW ...
I'm one version number back in both Logic and Garage Band so I'm not familiar w the newest version of GB ...
In the version of GB that I have it is very easy to have 32 bit files of each individual track to use in a different DAW .
GB has a feature called track lock . When you lock the individual tracks of a song / mix you have basically frozen the tracks ....w effects ...
once you hit play in GB , GB go's through a little song and dance and renders your locked tracks to individual audio files ...the beach ball spins for a while and then your rendered tracks are stored in a folder ...
Now I'm not on my Mac ...but IIRC the rendered audio is named in numbers ..not as per the track names...
I have done this hundreds of times ...I have taken the files and put them on a thumb drive and brought them over to my PC to work on them in SONAR ....
IMHO the important thing is to have good habits and keep a tidy file management structure ...
good habits means communication of all important info ...its important to have the songs key , tempo and an idea of the songs structure ....
If I take my individual frozen track files from GB and have the correct info to tempo match and create a SONAR project ...they will import into SONAR perfectly w out a glitch ...
once in SONAR I will have to deal w file management and re naming and deleting all the unnecessary GB orphans once my SONAR project has been organized ....
The opposite side of the coin is true also ...you can take a SONAR project of 1 , 10 ...20 ...or 50+ individual tracks
that were created in SONAR and import them one at a time into GB ....if you have the right tempo info every thing will line up ...
Now some people may ask well why do that ? it's only GB right ?
Well I don't know about you but my GB has some bad A$$ed 3 rd party $hit in it
+ it's real simple to work in GB ...
If I get tired of working in GB , all I have to do is open the same GB project in Logic and take it to the next level ...
by using better plugs and instruments ....that is one nice thing about GB ..if you have GB you can open up the GB projects in Logic ....in Logic you an finalize things to all audio and then export your whole mix as individual tracks an OMF file ...
SONAR happens to open up OMF file's pretty good
to the OP , maybe you can get your collab mate / singer to bump up his GB DAW skills ...that may help all across the board ....
anyway sorry about the ramble
Kenny
PS , IIRC , the only thing that GB does not do is export midi ...it can import , but not export midi ...
so if you guys are working w a lot of midi , it may be worth his while to pick up Logic or even Reaper to have that ability....
just an after thought ...