I prefer to drill these out with a holesaw of 20-25 or 32mm diameter, just means that our cheap plastic enclosures don't split!
Most of the boxes where I need to knock-out the conduit entries are metal. We do have some surface mount ABS boxes which have K/O's for use with conduit, but I rarely use them.
The urea-based back boxes which are most prone to splitting here don;t generally have conduit K/Os, but they do have "break out" tabs so that surface run cables can enter.
A lot of people seem to have trouble snapping these out without splitting anything, but the trick is to just use a junior hacksaw to cut the thin sides before using the pliers.