in terms of size and symmetry?
my current tri routine is:
dips
standind skull crushers
pushdowns (might add one arm instead)
For symmetry its awful, you gotta train BOTH sides 
One-Arm pulldowns are a great exercise, especially after you’re able to do some heavy weight.
Single Arm Pushdowns are the best 1-Arm Triceps extension movement. You can’t use much weight with Kickbacks or 1-Arm Dumbbell Extensions. A Better choice might be Tate Presses with 1 Arm but you’ll probably be tired after doing Dips and Skullcrushers so a Pushdown is probably the perfect choice.
The Best Triceps Exercises will Always be Close-Grip Bench Press, Dips, Rack Lockouts, Board Presses, Floor Presses, and JM Presses. One of these should be done whenever doing Triceps.
Rolling Dumbbell Triceps Extensions, Lying EZ-Bar Extensions, and Heavy Dumbbell Overhead Extensions come to mind as the best Triceps Isolation Exercises. If you can do 35% of your Bench Max with good form on a Triceps Isolation Exercise, then I’d say it uses heavy enough weight to be considered useful.
Pushdowns are fluff and are pretty much all equal except for reverse grip Pushdowns. If you do pushdowns, you should have already done a Big Lift that involves the triceps and a more worthwile Triceps exercise. The exception to this rule would be if you want to give your elbows a break. I remember Eric Cressey said he sympathized with other powerlifters for doing Rubber Band Pushdowns after he benched 400lbs for the first time and felt like his elbows were going to explode. Whatever the case, Pushdowns should be used to get blood into the muscle. Who cares if you’re using 2 10lb plates to get that accomplished?
Why don’t you jsut try it and see how it makes your arms feel?
You can also try and turn your body away from the pulley, so that you’re doing the pushdown from the side. Gives a whole new feeling to the exercise.
[quote]DanErickson wrote:
Why don’t you jsut try it and see how it makes your arms feel?[/quote]
If that was everyones outlook, there wouldn’t be much of a forum here would there? Just kidding Dan - I agree with you to an extent in the regard that different excersises will affect one person differently than another.
To the OP: When it comes down to it, it’s what works best for you personally. I know quite a few people who get enough work in their tri’s just doing large compound movements (dips, bench, etc.) and never do any isolation work - I however have to throw in isolation movements to see any gains at all.
So from someone who does isolation work - I do like the 1 arm tricep pulldowns (and pushdowns for that matter). Throw them into your next routine and tell us how it worked out for you in a few weeks.
- AB