MEFs as printed on CAA 1/2 mill charts are based on information available concerning the highest known feature in the associated area, including terrain and obstacles and allowing for unknown features.
There is no need to add the mythical 300 ft as that is allowed for - if there are higher obstacles already known about, then they will have been included in the MEF. If not, then the 300 ft will already have been added.
Beagle, he's not using the MEF figures but calculating the MSA from either the highest marked obstacle (plus 1000' & rounded up) or the highest marked elevation (plus 1300' & rounded up) either side of the track. Can't blame the guy for that, as that's what he's been told to do.
Nevertheless, I agree with you. It's much easier to use the sector MEF figures and add 1000' to get the MSA if you're using the 1/2 mill CAA charts. And if you use the Jeppesen ones, the sector MSA is actually already printed on the map.