I have to disagree. The condensate that most people, including me, find in their intercoolers is water with a very small amount of oil. This is coming from hot, humid air (think steam but not quite that hot) passing through the intercooler and condensing inside so that it's too heavy to be pulled through into the motor. So what you find in an un-drilled stock CAC is water with a tiny bit of emulsified oil mixed in. The oil in there comes from the PCV system. A catch can keeps the oil from gunking up the intake tract, CAC, and valves.Elkhart, the major source of the "condensate" is the vapors drawn in from the driver's side head to the driver's side turbo. THAT is what a catch can stops.
Drill a weep hole and have a boost leak if you want. But a good Catch Can will solve the problem (plus the build up on your intake valves ... that a Weep hole does nothing for).
The catch can captures water, yes, but in much smaller amounts. It collects a lot of fuel (and solves the fuel dilution issue completely... before, my oil reeked of it. After, it's not detectable by the nose, I'm sure a small amount would show up in lab tests) and some oil too. The oil is mostly emulsified by the water it catches. On a somewhat humid (but not wet) day, the area around the weep hole is wet. After several hours in the driveway, it's dry, which means it's all water and no oil, as the oil would not evaporate.
Fuel and oil blow by, and condensation are two different issues. N/A cars have catch cans and they have no condensation issues whatsoever. Port injection, forced induction cars have intercoolers with weep holes (Volvos, for one) and oil and fuel blow by are not as much of a concern on those motors but the weep hole is there for water.