Jiml,
I agree that 5fps is a good number for the max procedure. At the factory, we instrument the gear structure and work the procedure to get more aggressive as we watch the structural loads climb, more to the specific point. The touchdowns get to be 5 to 6fps at the peak, so your assumptions agree quite well with our test experiences. I have personally flown procedures where we hit 100% of the gear loads and the collective pitch stops, while dropping the rotor to the min limit, all at the same time. Not too much left in the aircraft at that point!
As to side loads, the combination of velocity and bank is a killer, the regs describe the design values as assumed side loads, with 80% of the vertical load applied to one gear inward and 60% outward to the other simultaneously. These are met with virtually no margin (not including the 1.5 safety factor, of course), done analytically.