No, SMS-speak is NOT acceptable except in SMS communication between friends.
When people become comfortable with SMS-speak in a public forum like this, they will increasingly become comfortable with the lazy, hard-to-read communication in other professional forums, which will then carry over to the extremely unprofessional use of SMS-speak when interacting with customers. My customers will not tolerate that level of unprofessionalism. If you wish to be perceived as world-class, as the best in the business, you MUST communicate properly -- and SMS-speak simply doesn't pass the test.