Question on Channel Routing in HEC-1

Any help on this question is greatly appreciated...
We have been reviewing a report in which the author states that they did
not use the kinematic wave routing method in HEC-1 because it (the 1988 version)
gives inaccurate answers whre the urban subbasin is long and / or very flat.
Is this a well known (real) problem? Was it limited to the 1988 version of HEC-1?
Is it still present in the later releases and HEC HMS?

Thank you in advance for any thoughts.

Brian Verspagen
Carter & Burgess