I understand the problem with CIPS is that it is not very flexible for our current 'lifestyle' of regular deployments due to exam dates etc . For this reason I took the CILT Diploma route through Logistics Learning Alliance - they were extremely flexible even giving me a course pack to deploy with and accepting work by fax/e-mail/CD or post!
CILT also had the advantage as being acceptable for credit towards a degree I am not sure if CIPS is? One other question with regard to CIPS is its applicability outside the Public Sector, and how long it stays current, I always understood that a lot of it is commercial procurement law which seems to change regularly so studying CIPS 5 or 6 years before you are due out may not be that useful- just a thought.
As for Durham College I have spoken to them about courses in the past but have never studied with them, have you asked the ELC what feedback they have received? All ELC students have to provide feedback at the conclusion of the course so they might be able to provide some feedback on the admin and tutor support they offer.
What ever you choose good luck, its not easy doing distance learning but once you get 'into it' I found it really rewarding.