It's cheaper than CA. Sure you have to spend about $35 for the product, but if you break it down cost wise compared to the quantity, you save alot of money.
You don't have to build a dust free environment, but if you do, then you don't have to sand and polish and end up with a pen that is many times more glossy than CA can be no matter how much you might polish the CA.
You only need one coat, the stuff is so thick you see a beautiful <in my opinion>, horizon in the finish.
You don't ever get clouds in the finish.
Sticks like mad to metal, but if you use delrin bushings, that problem is no longer a problem.
If you get dust on it, you have to sand and polish it like you would CA, and then you get the same gloss factor as CA, but you do still get the thick horizon.
You can sand it next day if you use water and care, but like i said, keep the dust away, and you don't even need sand it, looks better unsanded, like it is in wet glass.
If you are in a hurry, this isn't the finish for you. If you have lots of time and CA is a hassle for you, this finish will knock your socks off.
As far as hardness goes, I believe it will outlast CA. Just think about the objects that have system 3 on them..bar tops, tables, stools..look at the abuse those get, especially a stool, and the finish keeps on going. It's really not a difficult finish to apply at all, I just like to be sure people know what they are getting into should they want to try it. Let ya'll know some of the downsides I've experienced, and experiment with ways to counter the downsides. You look at a product like enduro, or laquer, and the downsides are practically the same..dust and wait time. I think enduro is probably the best, and deffinitely the strongest finish if you use the strengthening agent available for it. Only real difference between that and this is the added gloss and thickness of the system 3 is what I like. It all comes down to what you want your pen to look like.