DSC1 came about some years ago. It is recognised by most institutions, such as the FC as the industry standard to achieve. Added to this is DSC 2 which is proof a certain extent that a stalker has achieved a reasonable standard to put deer carcasses into the food chain. Again this is the recognised industry standard.
Level One costs about £300 for a 3 day course. Usually run by an Assessor, who must have achieved an assessment qualification to run the course. And usually another experienced stalker, or Approved Witness.
When you have achieved Level 1 a candidate can then go on and take their Level 2, which is with an Approved Witness. One ICR is now required to pass. The fee to register for this is about £180.
These PDS courses are usually run by non Assessors, and are as a rule expensive, to the tune of £500 per candidate, and from what I have seen are less than a day, and do not cover anywhere near the subjects that DSC 1 does. Which as a rule is a 3 day course.
Those who choose to take PDS course, will find that they cannot then go onto to take DSC Level 2, as they do not have DSC 1.
Most leases, especially those offered by the Forestry Commission, and other bodies require a stalker to have DSC 1 and 2 before applying for a lease.
People can make their own choices, but if you are starting out in the stalking world, my advice would be to book yourself onto a DSC 1 course.