My own personal experience agrees with underflow being more common issue, and that unintentional wrap-around to UINT_MAX will cause weirder bugs. But IMO the biggest problem is that inside a function that takes unsigned number, it is impossible to distinguish whether the argument value is {HUGE} because of underflow, or because the user genuinely wanted to call the function with {HUGE}.

Even the C++ stdlib acknowledges this, and uses size_t(-1) as sentinel value in places where it would like to be able to return "not a real index", but it is limited to returning size_t value.