well I got some great news.. I think the upgrade to support large file sizes was successful. Everything appears to work correctly.
Things went so smoothly I had an idea.. My idea was to take the delphi 6 source (I own delphi 6 Pro) and replace the base TStream class with the one found in delphi 6. I had my doubts about wether or not this would work, after some trial and error I was able to compile the code. I then uploaded & downloaded a 2.3gb file stopping and resuming a few times. I then procceded to test the file with FlashSFV.. hrmm slight problem, it seems FlashSFV has problems with large files too. It was able to correctly generate the CRC but the progressbar/file size was incorrect. Ok so I created a SFV with the original and compared it to the copy I uploaded & downloaded. (several hours later)
Success..
I'll post a new build experimental tomorrow