To the above it is clearly stated in many places that not only is it the case the smooth operator achievement doesnt give you the foxiest achievement but they actually say it is ill advised to even rely on these XP achievements as verification of having stayed on track for ultimately getting the foxiest of all fox achievement.
I will link sites but a for instance was offered, suppose you took down a soldier, when you left the area you at that point heard no alarms but they found the body latter and set the alarm off, out of your detection, if you finish the level after they set off an alarm in that portion of the facility you will void the foxiest achievement. The deus wika also says to be extremely careful and given how much game play time is needed its best to reload if you are even a lottle unsure. I personally have a mini book i am writing down a save for each level..then underneath if i am concerned of a possible alarm i missed, and using a few saves 1to 3 IN each level if i am concerned and want to back track, if its a long level i may use 2 instead of one saves in a campaign in case i dont get the achievement but think i have an idea of where i might have blundered
But most important its unsafe or unwise to use a different XP achievement to substitute as an assurance you recieved a different game achievement. Here are the links below:
http://deusex.wikia.com/wiki/Foxiest_of_the_Hounds
"It should be noted that simply getting all the bonuses does not guarantee the acquisition of the achievement. If, for example, the player leaves a body of a knocked out enemy in a place where other patrolling guards may potentially find him and completes the objective fast enough he will still get the Smooth Operator bonus. But eventually the body will be found and guards will sound an alarm (it may even happen out of player's sight), which in turn will nullify the Foxiest of the Hounds. So it is recommended to play cautiously and not to trust the XP rewards too much."
also check out the link for smooth operator in the above page as a newbie i have a limit on links i can post
Interesting things like a soldier seeing a knocked out buddy may trigger an alarmed state but they may or may not sound an alarm...however if a camera sees a downed body it will sound an alarm
This site is also expremely helpful as its intent is to serve as a walkthrough guide for ALL achievements in one playthrough so they also show secret achievements as well as focus on the foxiest approach and pacificst approach.
http://www.trueachievements.com/deus-ex-human-revolution-walkthrough.htm?page=2
Each subseqent page is dedicated to each sote in the game and a loose walkthrough highliting only the main points for the achievements vs detailed approaches and maps.
To the mods that delete my last post it was a continuation of THIS ..ie not just a post with a link...BEACAUSE your rules didnt allow me to include the third link as a contrasting option for those who would prefer the more detailed approach vs the water downed basics given in this post
******I can only do what site allows it didnt make that detailed guide any less helpful to walking people through it. I would rather you add it to this post please instead of deleting since my hands are tied at a noob status i cant even comment on my part 1 post because i am a noob. Its so restrictive we cant function let a lone maintain mod approved standards of content or substantial post content beyond links thank you