Acronyims and abbreviations that are used in professional literature and data sheets that will need to be read and understood by any one wishing to work in this field would be acceptable. Thus RTM would be acceptable but RTFM not! the "F" can not be concidered professional. Spare me the other meanings you might claim - we all know which F-word was intended.
SMS expressions Would never be found in professional literature or I hope Websters Dictionary.

Communications is the hardest thing that we attempt on a day to day basis Thus anything that makes the process less effective is a step in the wrong direction.

By the way what does SMS actualy stand for. I know what it is and where and why it originated but have never liked it. Terry