I also concur with Christian's points above. Implicit Enhancements are normally for situations where you have no other means of enhancing the system or the provided enhancement points won't work. They are also for situations where there is poorly designed SAP delivered code with no enhancement options(such as the ADRMAS idoc in ERP).
In the long run you will save more time and effort by enhancing your system in the proper fashion with the tools provided instead of going down an alternative route. It makes supporting the system much easier for everyone.
Take care,
Stephen