Just had a quick-ish play around with the newly provided wake option (needs setting on host and within missions).
You get a sudden and violent jerk motion when 200 feet behind the Kc-135 (only AC so far noticed this) but only behind the wing tip, there is nothing noticable behind the AC -I would expect some rough air?
I read on ED's forums that some FR loss was experienced with this on -I did also but not measured how much as such yet.