Speaking from strictly personal experience here so take it for what it is worth.
When moly first hit the scene, I was working up new loads for two different rifles. My 25-05 and a brand new Sendero in 7mag. The 25 had already had several hundered rounds through it and was properly broken in from the start. The Sendero however was unfired. Before ever chambering a round, I lapped the barrel with 600 and 800 grit compound. This put a mirror finish on it, and drastically improved the bore. I coated the bullets myself, using the recommended techniques, and modified it to work somewhat better for my needs. I got a lot of my information at that time from an old forum on Compuserve from a man named Dan Hackett, who has done extensive testing with it.
I have since read many pages of why not to do this proceedure for any barrel, however I have personally noticed none of the drastic damage noted from these reports. My rifles are cleaned on a regular basis, and accuracy has held up just fine. Neither are custom barrels so that might make a difference.
However, in the overall scheme, I have been able to get better velocity, as well as more consistant groups while using it verses not out of these particular arms. I also went with the moly on my 7x30 Waters in order to achjieve the velocity I wanted for the particular load I worked up. I simply could not get there with out it. The same applies to the load I settled with for the 7 mag. THe moly I use is 16 microfine and I get it through McMaster-Carr. From what I have seen it appears to be a tad finer than some of the kits. I do not use the steel balls when tumbling bullets. I simply clean them with some solvent or polish with untreated corn cob media and tumble in a drum type tumbler, the latter seems to work best. You have to get the polish removed in order for the moly to adhear properly.
Like I mentioned, there are some real horror stories out there, but I personally haven't seen the damage noted by them. I have been shooting it since 1990 and all guns still hold their groups and velocities as they did then.
Like I said, it is to me more of a do or don't sort of thing. To me, in the applications I have used it, it has worked quite well. This has mostly been high octain loads through the smaller bores. I am sure that you will get more than just my opinion on this so the untimate choice will be up to you.