Instruction 
Deformation motion Blur with Linear Interporation
Make sure point number doesn't change while shutter is open.
If shutter offset is 0 and Shutter time is 0.5, then "f - 0.25 <= f <= f + 0.25" should keep point number.
Normal time blend may change point number before and after integer frame. Here is an simple new time blend to use the same geometry during "f - 0.25 <= f <= f + 0.25".
Deformation motion Blur with Linear Interporation and subframe motion
Once you get correct motion blur, now add noise. This is effective when you work on sparks or something.
Deformation motion Blur with Spline Interporation and subframe motion
"Time Blend" above still interporates linearly at subframes.
Ideally, we should make another "time blend" node for non-linear interporation. In subframes, particles follow spline curves made with integer frames above.