Personally, I would say it is worth the extra $70night. Right now I am contemplating paying an extra $120night. When are you going and may I ask what is your rate?
We stayed at BC concierge last summer. It was nice not haiving to go to a restaurant for at least one meal a day. I am not only referring to cost but to the hustle of rounding everyone up in the AM and the time it takes to eat breakfast before heading to the parks. We figured eating breakfast in the lounge saved us at least 30 minutes in the morning and $25-$35 for breakfast. The bottled water for the parks was at least another $10-$15/day (I believe bottled water costs $2.65 in the parks). We always came back from the parks after lunch to cool down and stopped at the lounge on our way back. Cool drinks and snacks were available and we filled up a bowl, grabbed a drink and took it back to our room. Kids would go back for refills if they wanted to. Evening snacks and desserts are also available. Did we save $120/day? I don't think so. Did we save $70/day? I would say pretty darn close. Even if we wouldn't save $70/day, I would have to place a value on the convenience of the amenities available at the lounge and concierge desk. Some people go to the store and purchase breakfast items and bottled water and rent a refrigerator for the same convenience. I am the penny pincher in our family and I would have no problem doing this but my DH will not let me (us) go through the hassle of doing this. (Believe me, we have had our arguments!) But since we started staying in concierge, it is hard to think of not staying there. In the end, we will probably end up staying at the YC concierge because we love the Epcot resort area. Hopefully, better discounts in concierge will come available as they have in the past. Poly also has an excellent concierge.
In closing, I would say if you can afford it, try it. I doubt you'll be dissappointed. If you plan on several character breakfasts, you might want to reconsider the extra cost. By the way, the concierge staff was also helpful in not only getting PS when we couldn't get them through Disney Dining, but great times with great views. Good luck on your decision!