If new HD was added to 129 and 72.7 or 77, subs like me with 119/110/61.5 setups would be screwed.
119/110/61.5 is not a standard install. It was just used in certain cases where the 129 slot did not have line-of-sight or for the earlier locals that were added to 61.5 prior to Eastern Arc.
HD subs are supposed to have 110/119/129 or 61.5/72.5/77 and I expect that whenever existing subs are allowed to have EA installs, then the 61.5<->129 mirroring will cease.
To answer the Original Poster, Ciel-2 helps Eastern Arc customers in two ways:
1 - New channels could not be added to Dish Network, until the space was available on both Eastern Arc and "Western Arc" at the same time.
2 - Ciel-2 has 145 spot beams, included a number in the Eastern USA, and it is possible to make more space on Eastern Arc by moving some EA markets to Ciel-2 spot beams (especially the oldest ones that predate EA, so the customers already have a 110/119 dish).