You forget an important point: 6RD is developed for large amount of small customers (e.g. home users). Giving them /56-/60 should not be a problem. 6RD is not universal! Larger customers your should implement dual-stack solution and give them /48. One size does not fit for all!
I consider it a problem if anyone is giving private residence customers a /60. Nobody should get less than a /56 block and if anyone believes that RIPE rules force them to give less than a /56 block, then RIPE should either clarify the situation (education) or we should change the rules. Yes, I agree that non-residential customers should get a /48 and run dual stack on their network, or use other transition mechanisms like Teredo, 6to4, etc. The total cost of transition will be minimized this way. --Michael Dillon