Depends on:

• Material: DV does not require the same bandwidth as AVCHD or RED 4K.
• Number of tracks: a single track does not require as much bandwidth as 10 tracks.
• Nature and amount of effects/transitions, native or third-party.
• Amount of memory installed and pagefile size and location.
• Graphics card used.
• CPU used.
• Clock speed.
• Disk I/O setup.

So the question is a bit broader than you may have surmised.

a sandy bridge i5 2500k system with a 2 raid 7200rpm drive

That is pretty minimal for a setup.

I don't know if there exists such a paper, but with CS6 and a single track of AVCHD, I saw transfer rates of around 50 MB/s, with six video tracks and an adjustment layer with a combination of AVCHD, XDCAM EX, HDV, DV, Canon MXF and RED 4K is had transfer rates in excess of 300 MB/s.

You better have a look at Adobe Forums: System requirements for CS5 and realize that your workflow falls solidly in the Difficult category. An i5-2500 and a 2 disk raid0 will be borderline and you should expect choppy and jerky behavior.

CS6.01 is a little better, but far from your nominal 5 MB/s. If this is a confirmed bug, then it not only applies to AVCHD, but to other formats as well.

Playback of a single video track, no effects, no transitions, just clips butted together in CS6.01 gives average transfer rates of:

AVCHD around 32 MB/s

Canon MXF around 62 MB/s

Notice that the nominal rate of MXF is 50 Mbps or 6.25 MB/s and for AVCHD it is 24 Mbps or 3 MB/s. But those nominal rates only apply to the recording rates, not the unpacked material used for display.

not the unpacked material used for display.

Decoding happens at the CPU, after it's read from the disk.  The disk read rate for DV, HDV and AVCHD, including audio and overhead, will be around 5 MB/s.