What a topic to talk about......
My left leg is stronger then my right. I do alot of 1 leg training and I have an SRM crank. So I am able to see it when I do my 1 leg training. Its a big difference in my legs. Sometimes about 10%. I focus alot to try and make it even wattage but if Im watching a movie then I drift off and I have that 10% margin again.
I dont think its a huge concern about having one stronger then the other. I think my left is stronger from the sports I did as a kid. Im right handed, which means I jump off my left leg. I played lots of basketball as a result, which explains why its so much stronger. But Im not too worried about it because I believe it hasnt affected me too much.
As for how much you should pull up and techic in the pedal stroke is another thing.
Pedal technic is very important. Some people have the "heavy leg" which is they dont pull up at all and the other leg has to help it, many say its not a concern. But I believe its very important not to have a heavy leg.
You can have two cyclist that are totaly the same in Vo2max,etc..... however 1 cyclist has a "heavy leg". They both go to do a medical test to work out there watts at a Lactic Level and they both produce two difference result, however they are the save. The reason is 1 has the "heavy leg", cyclist legs are not light and if your ever on a mag and relax your right leg when its at the 6oclock. Then you pedal with your left to apply power to the chain and lift your leg. You will notice its much harder then to pedal when you right leg is not against the pedal. In fact your legs are working against each other. So, yes you should pull up. Now I dont believe you should pull up heaps, I think too much is a waste, but you should pull up just enough to make it easier for your other leg.
On paper you could produce 12ml of LA at only 100watts when your legs work against each other. So the idea is, to do it the other way around.
Ways to improve you pedal technic are:
High Cadence on the flat.(very easy with a power meter)
If you did a bunch of 1leg training, then into the hills you will notice the difference it made.
High cadence on the flat:
If you were to ride a hill at an even wattage, say 300watts@90cadence for 5mins it would be quite easy. Doing the same on the flat is much harder, because there isnt that resistence on the crank. You can have terrible pedal technic and still do 300watt very easy on the hill. You will notice doing it on the flat you will have a lot of dead spots. Your power will be all over the place, too high and too low. The more you train your pedal techic you will be able to have a better avg of power output on the flat. by increasing the Cadence, >100. It will be even harder. This will also help in the hills.
hope it helps.