Bruce McKenzie - Were the problems with CentOS 6.x just for SCST stuff, or more in general?
I looked at SCST stuff with CentOS 6.x yesterday, but it seemed all very complicated and I wasn't in the mood for it. (getting over flu). It sounds like getting SCST running on recent Ubuntu is easier than on CentOS.
For someone already familiar with RHEL/CentOS/SL though, using the "out of box" OS provided drivers is definitely the easiest way to get started. If they need SRP support (thus having to manually compile in SCST), it seems a bit painful.
Jim Beam - With Mellanox OFED, I'm not really sure of the benefits of it yet. I've only used it briefly over the inbuilt support, so I could use an older version of Mellanox Firmware Tools to talk to my older Voltaire 9024D-M switch.
The testing gear I work on with Infiniband (so far) doesn't really push the envelope (yet), so I've not really had to explore alternative options all that much.
(note - edited for typo fixes)