I ripped "Pacific Rim" dual layer (about 37gb) using imgburn and these were the numbers I got:
Operation Successfully Completed! - Duration: 00:24:56
Average Read Rate: 24,751 KB/s (5.5x) - Maximum Read Rate: 34,961 KB/s (7.8x)
This was using a Sony BD-5300S blu-ray player/burner (stock) on a Mac Pro - OSX 10.9 host running Parallels 8.0 and a Windows 7 x64 client. I used to use a LG-hg20? but when I removed the rip lock I started noticing artifacts in some of my rips, plus it caused sleeping/wake-up problems on the mac.