Get tough on telecommuting: 6 questions to ask before you say yes

Managers should also consider the possibility that telework can become, for some workers, too good of an offer - high performers might forego advancement, or even leave the company, in order to continue teleworking. "It becomes a lifestyle," notes Keefe. "I've had a couple of key people leave the organisation, so now I'm more cautious about that."

Ironically, the opposite situation can also occur: Employees who pushed for and received permission to telework may find it's not as wonderful as they expected. They may feel lost, disconnected from the workplace and the office banter. Rather than admitting the mistake, they may look for work in another office.

In fact, there is a higher degree of churn among teleworkers today than in the past, according to Sean Ryan, an analyst at IDC. Statistics indicate that, for whatever reason, telework is not a permanent arrangement, he says. "They telecommute for a while, but then go back into the corporate world."

Indeed, research from 2005 published in the Journal of Management suggests that allowing insufficiently screened employees to work more than three days out of the office results in long-term decreases in productivity and staff morale and increases in staff turnover "as they move on to jobs where they feel more included," says Gartner's Morrison. 

In conclusion, the consensus among managers who've had it both ways is that telework is never an all-or-nothing proposition. Whether you ultimately decide to allow an employee to work from home full time or part time, or not at all, your decision should be the result of careful consideration of the needs of the worker, his colleagues and managers and - most important - the needs of your business.