I like them for hops, but last I saw they were really expensine for grain.
This had me thinking when you posted it.
So most places charge for delivery and they can vary, I usually go to MM for everything but then realised that I wasn't happy paying 7 odd quid every time for delivery.
The MM malts vary in price whereas CML don't appear to.
I did a very quick comparison between the two and this is not complete by any means.
MM for 5kg of Pilsner Malt best Malz = £8.00 + £7.20 = £15.20
CML for 5kg of Pilsner Malt (unknown) = £14.45 delivered.
CML don't change the price depending on the grain. I've yet to brew with CML grain but if its decent then I think I may have a new regular.