When we went in January, we too had an early flight 6:20. We left home around 4:30 and got there around 5 or so. There were more people there than I had expected and we were in the new terminal. It took a while, perhaps 30 minutes to get through security. We walked to the gate, grabbed breakfast at one of the few options open that early, and waited another 5-10 minutes before our group boarded. We were at the back of the plane, so our group was one of the first to board. We were able to do a half day at Hollywood Studios before heading to the luau at the early seating. As for being wiped out...it will happen regardless. That's what coming home is for - catching up on the zzz's. We were all out every night until at least 11 pm or midnight. And we slept great!!
We had the Deluxe DDP last time and stayed at Caribbean Beach. One of the main reasons I did the deluxe was because we did the luau at the Poly and it cost 2 credits. The show was great as was the bread and salad, but the rest of the food was alright. It was going to really limit us for the remainder of our meals. We are DVC members as of February and I am still contemplating whether or not we will do the basic DDP and we stay in a studio or not do it at all and we stay in a 1 bedroom with a kitchen. DH and I want to eat at one of the French restaurants in Epcot and I don't think they are on the plan. Fewer people are on it than they were before. And gratuity is not included like in previous years and appetizer not included in the basic but it is on the deluxe.
It's not as great of a deal as it was before I think. But, I kept receipts and wrote down what it would have cost if we had paid cash. And my kids ordered lobster! Imagine that at Disney price.

I think the basic plan at 39.99 pp is a better deal than the deluxe 69.99 pp above 10 years old (I may be off on the prices).