My biggest nit with all these shots is that the processing of the subject doesn't match the processing of the background - the subject is too cleanly processed. I'd prefer to see a better blend of styles, but that may not be what you are trying to achieve.
I hear what your saying and I think that is the idea behind these composites so that the person jumps right out at you. I was actually holding back on the processing of myself so I did not look to grungy…I thought it worked but I can also try it the other way.
Here is some references
this guys stuff is a little more clean than grungy. I like these composites.
I think you could benefit from processing the subject closer to the manner that your intended background is processed.
That seems to me to be at least part of what makes the images in the link work better.