I think it makes a big difference. I have it on each and every kit I use and have done for a long time. Not even sure what the alternative options for that slot are any more! Think there is 1 for making the guns more accurate or something (?) but I don't have accuracy issues
I have played the specact guns to get a gold medal on them but I was nearly suicidal doing the m16 and m95. Only hardcore preserved my sanity. I honestly don't understand what the m95 does with the bullet after I press fire. I am quite handy with the GOL or m24 but the m95 is beyond terrible!
The sooner you get behind, the longer you have to catch up.