Jim, I see where you get 1300' from but not 1500' - we use 1000' and don't overfly any radar contacts below that.
The normal Non Representative Allowance added to terrain overland is 300' and the Maximum Elevation Figures on our maps reflect the maximum terrain plus the NRA. Over the sea with no other structures, this figure becomes 300' and does not need to be rounded up further so the MSA over open water would be 1300'. But we base our safety altitude on the highest terrain we are likely to fly over, not the MEF so ours is 1000' over open water. The advantage of a good radar is that it will see any vessel or structure (especially those nasty windfarms) and we just avoid them below 1000'.
All that one of the SAR operators needs to do is post here outlining what they do when letting down IMC to a radar contact or GPS position to effect a rescue or carry out a search -the exemption for approach and landing is not valid in this case.
We have a specific exemption in JSP 550 to operate IMC below MSA over water because we have clearly laid down procedures using Rad Alt and on-board radar for vertical and horizontal clearances - this is why we carry a Radar Operator and have a large radar swept arc 330 degrees.
I know this all seems like semantics but this is a capability that is not matched by the S92 or S61 and needs to be addressed before 2012.