I like to use it when dieting seems to help keep some of my strength up. I wouldnt see a problem with it dieting unless it was for a show and you need to cut out all bloat, or if its a creating that has a bunch of sugar.
By all practical purposes you can use it all you want. I myself wont touch monohydrate and stick to ethyl esters. They greatly reduce any water retention and the total serving is much less with no extra carbs from dextrose or fruit juice needed to aid in transportation to the muscle cells. I would cut it out at the end of your pre-contest program to keep things simple. A few simple changes to your supplements is all you need to do really.....the biggest change should come from the food you are eating.