That list isn't entirely correct, as it says the HS-225BB can't be modified.
Not true! I just modified one yesterday. According to that scale, I'd say difficulty was a 3.
And the HS-225MG is harder, more like a 8, because its really hard to remove those darn metal pins . . .
Also yesterday I discovered that a dremmel is a great tool to cut away that stopper bit.