I used 50 lights on my tree at 7 watts a piece, so that's 350 watts.
Now I use 50 LED's at .95 watts a piece, so it comes out to 47.5 watts.
That means that I can leave the LED lights on for 7 1/2 hours before I'd use what the other lights used in one hour...
I reluctantly gave in and switched last year for one reason: It was getting hard to find those old "GE" C7 & C9 bulbs that had the vivid "Red, Blue, Green and Yellow" colors on them. They're on Ebay but many folks are bidding really high on them. Plus, the newer ones in the stores today are NOT even pretty. Blue is my favorite but I was seriously disappointed in the newer shade of blue.
As I said in another thread, if it's brightness you're looking for, regular single LED bulbs are not for you. I found a place that sells all types of LED Christmas bulbs and most of them have 3 LED units in each bulb. I've replaced every one of my old GE bulbs with LED's but I still mix in some bubble lights (about 10) for that "old style" look...Here's the site:
BulkLights.Com! "Go Green" Energy Saving LED Lights, Light Bulbs & Holiday Decorations!