I use the gisteq tracker.
The good thing is that you can several cameras with it, it runs in your bag/pocket and you can shoot as you're used to.
When you get home you can read out the small unit and than add the GPS data to your RAW files.
The website claims it works with Leaf and Phase RAWs but I have had no success with the leaf files, it's not a big problem however, the files I need tagged are converted to DNG and it works great.
All other standalone units I know off will only tag JPEG and that's useless for me.
So I would advise you the check the gisteq out.
Don't expect much of their customerservice however.
Leaf offered to help them out in getting the leaf files working but I never heard a response except that I could get my money back.
However as long as it works with DNG it's ok for me.