Yep that TC website is a load of krap!
Personally guess that pattern discs ok for rear as they don't do too much work - I've always used pattern pads on the rear without any problems and TC pads (and discs) on the front.
I see your thinking, but what's the price difference of full retail price of pattern discs & discounted OEM discs? 
How much are pattern pads? TC rears are/were around £20 .................. My R Class's rear pads are all but £100 from MB

Pattern pads for the rear, incl pins and springs, were about £12. Used them on last 3 Omegas without issue. (saving about £24 in the process - not to be sniffed at - bought me getting on for 1/4 tank of petrol in the Jag

)
Similar price to your Merc for rear pads from Jag - pattern (Pagit or Mintex) around £25
Never had to replace rear discs on Omega so don't know prices - shows how little work they do