RVM/VMM/OVM/UVM provides rich set of features that can be used to develop a sophisticated test bench. Extending your Driven/monitor/scoreboard/sequence directly from the methodology may not be an ideal solution with respect to product specific requirement. The ideal way is have a set of base class extending from the methodology class which adds specific requirement which will be product line specific. Having company/product specific base class helps in better reuse and isolates the users from the changes introduced due to new releases in the methodology. When ever specific base class is changed it can be qualified with the supported version of tool,methodology and VIP. This approach also helps to incrementally move towards the latest releases of the methodology ensuring current development effort is not stalled.