I've used the metal one to brush across units that have been almost completely flattened.....no way you're gonna get even spacing again, so i go with the "something is better than nothing" approach. it also works well for scraping REALLY caked evaps.!!LOL!
I do a ton of hail damage repair or just because I am waiting on a vacuum. For the most part it is carriers that seem to be a magnet for hail damage. I use supco FC1617 combs. I keep about twenty on the truck. They work good even on heavy damage if you don't get greedy. A decent sized carrier can be straightened out surprisingly well in about 15 min. Of course always always keep a pocket screwdriver for that fin that always folds and wraps over the next. Fresh combs take patience but once the teeth get a little rounded you can fly through it.
After watching the factory guys use fin combs, it helps to use a light lubricant to make the comb slide on the aluminum easier. Just have to make sure and clean it after your done. I have used soap bubbles, diluted dish detergent, wd40 and such it helps the process tremendously.
TANSTAAFL - There ain't no such thing as a free lunch!