I am currently using a variable rate plan from my electric provider: Amerin IP, It's an Illinois/Missouri energy provider. We have been using this for about 3 years and each year we save about $300.00 to $600.00 compared to other customers who don't use the plan. I honestly think by comparing our old bills to the new bills we actually are saving about 75 to 100 per month! It's called "Powersmart Pricing"
We pay for our electricity at an hourly rate, that is variable. They send me an email if it goes above 9 cents per Kwh, the most costly times are right after work on hot days. and about an hour in the morning. A few times last year , in the late night it was a negative number, that meant they PAID us to use electricity then.. Who would have thought that???. We did change our usage pattern by doing all laundry at night, our washer has a timer and we use it to do a load after midnight. Same for our dish washer, we wash dishes at 2:00 am. We replaced all lights with CFL bulbs. Cell phone and other chargers are on timers that only charge from 2:00 am to 5:00 am, Of course we do charge as needed, but I also charge at work

. We also "pre-chill" our home by using the air conditioner and setting it lower than necessary before the more costly times, then turning it OFF when rates go higher. We sleep very cool, and then close up the curtains, and make the house dark using shade as our friend.
The one thing that did surprise me was the added costs to the plan, the fees involved ( participant fee, delivery fee) and the added taxes that are all hidden in the regular Kwh cost if you are not in the plan. Even with those costs ours is still WAY cheaper.
They don't "control" our power as some companies are doing, I don't think I like that. There are some times where I HAVE to turn on the air conditioner!
Investigate it, ask if you can talk to others who have tried it. I know that when we signed up for ours, it was a yearly commitment. I was also concerned that it may cost more. And yours might. Good luck!
Edited to add I just read more about the Energy Plus plan, It looks like that one will be variable on a monthly basis. Not sure how that could add value as we save money by using the bulk of our power during the low times each day. If it's an average, then how is it different than your local company: other than the miles or credits. If that's all I wanted, I'd pay for it with my rewards credit card.