3.7.15 here too. I'm not seeing any newer versions for GB. There may be a newer version for ICS. I will check my Prime later. I have seen where JB has some changes though.
I was unable to download or update over 4G Wimax on version 3.7.13, but with the version 3.7.15, the bug was fixed and I can now download or update over 4g Wimax again.
I bounce across 3G/4G areas and have never had any issues downloading/updating in any area with any version. My issue was that I had too many set for automatic updates which would download when I'm on the internet looking up something which would cause a lag.