Regarding locking each configuration separately, isn't that functionality already implemented for Matrix builds via the "Run each configuration sequentially" checkbox? Since that functionality is already supported it does it really make sense to have Locks and Latches duplicate it? Specially at the expense of being able to lock the 'parent' job.
In our setup we have a need for an exclusive lock for jobs A, B, C and D, where C and D are matrix configurations with dozens of individual, configurations (which need to run in simultaneously). We need to prevent job B from starting while C or D are running. At this time we haven't found a way to accomplish this, but Locks and Latches would seem ideal for the task - if it didn't lock the individual configurations.
Please reconsider or add an option to provide this support.