working while training
Yes - well sort of.
Ran my own business at the same time as going from zero to CPL I/R. To me it was the right decision as the business was very viable during that period of my life.
The down side however was considerable. It took longer then I antisipated - all of 5 years.
However the real down side was that it was much more difficult to completly switch off from business and just concentrate on the flying. Also due to one particular business upset I had to leave my I/R course after one week, only going back one year later to finish it off. The overall result was that I took more hours to gain my CPL than I would have done otherwise. It was also much more of a strain and I think I would have enjoyed the whole experience more if I'd just have concentrated on the flying.
At the end of the day, eveybody's situation is different and you have to do what you think is best for you. But whatever you decide there will be pros and cons.