As someone working for a 'Carrier' vendor - I can tell you straight up that LSN(Large Scale) or CGN(Carrier Grad) NAT are big sell points (i.e customers are asking for them).
Personally out of the various RFC's and schemes i've had the displeasure of perusing for V6 to V4 access NAT64 to me seems to the be the least evil. It is the ONLY solution which can easily remove the need for upstream fiddling if the CPE implements it, i.e the bad stuff at least stays on the edge of YOUR network. You effectively need the NAT64 module and a DNS proxy sitting on the CPE - all the various other RFC's require some level of ISP/Carrier interaction upstream to make things work; or break in interesting strange ways for the user (not that I am saying NAT64 is perfect). I know which I would prefer to see widely adopted. Also under the general guise of WHY you need NAT at all in IPV6 stacks... the ONE good argument is for easily setup Load Balancing. -Joel @aenertia http://gplus.to/aenertia
