Bummer, looks like gpib is busted on mainline kernels and not just the rpi stuff, dangit.
The Agilent is working 100% in my Linux Mint 17.3 x64 - (Should be same kernel as on Ubuntu 14.04)
3.19.0-32-generic #37~14.04.1-Ubuntu SMP Thu Oct 22 09:41:40 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
And it's working on my Raspi v1 , with Noobs 1.41 , updated to the raspbian,org kernel (that won't work on a Raspi v3)
/Bingo