Ditto here. Each crew member carries a DeWalt (with extra battery) and we always have plenty Lennox "fire and rescue" blades that do the trick quite well. We have countless areas where trees were planted too close to irrigation lines and the consequences are broken/pinched pipes.
When I design a new system I always take into account where the trees are already located and avoid them. When I design an area where trees might be planted in the future I horseshoe the piping in the area along the edges instead of running pipe down the middle. In fact, I have to go out to a site this morning and "witch" for existing QCV lines. They're planting 75 trees today and my witching markings tell them whether it's OK to plant a tree in a specific spot or whether it has to be moved. Cuts down on a lot of system repairs.