is() check should always be executed when instantiating a model

[PeterWippermann]

In org.senchalabs.gwt.gwtdriver.models.GwtWidget.GwtWidget(WebDriver, WebElement) there is an assertion:
assert is(getClass()) : "Not actually a widget, shouldn't be wrapped up as a widget";

To me this is a very useful check at runtime. However, since it's implemented as an assertion it isn't executed by default, since assertions are turned off in the JVM by default.
Of course, I could turn on assertions for myself but this would mean I would have to ensure they are turned on in all our development environments and I would have to confige my CI machine resp. my Maven config to have them turned on there as well.

So wouldn't it be a nice alternative to implement this check in an if-clause and raising an exception? Or does this have any significant drawbacks, e.g. on runtime?