I have been using PemnBGetFile for quite some time to download very large files (upwards of 20MBytes) from our agents.
The only issue we appear to have is that downloading from Patrol 3.5 Windows agents to our Solaris server does not work.
Downloading from our Patrol3.6 agents of all varieties (we have Windows, Solaris, HP-UX, and Linux agents) appears to work without problem.
The executable that runs on our Solaris server and performs these downloads was built with the PEMAPI that came with the Patrol for Unix 3.5 agents.
Maybe we're just lucky...?