EGTC,
I usually just use the MEF + 1000, unless I need to fly lower than this to get under controlled airspace
The MSA is not a prohibative altitude when VMC. The idea is to provide a yardstick by which you may more objectively decide that you should not proceed if you find the cloud base is moving below the MSA.
In addition, if you were to inadvertantly find yoursel in IMC, it is the altitude you should climb to if below (to provide a reasonable level of leeway for a somebody whose workload just shot up) or descend to when above (to minimise icing). For those reasons, you should determine the MSA regardless of the airspace you will be travelling in/under/over. Once you are in an IMC situation for which you are not rated, issues such as being in the Class A TMA are a very distant second
