Yeah, I tested both provo and disco masteries when they first came out, and again when the final changes were made, and I found the same thing. For disco, what you get from the mana expenditure just isn't worth it. I tried it on an archer with substantial leeching in addition to 12 MR in the suit and wasn't able to keep it going for more than maybe 8 seconds total. Since the cost to re-cast is pretty heavy (not to mention the time it takes), there's just better uses for my time and effort than trying to force a bard mastery into my process of killing things.
I'll stand by what I've been saying all along, that the way the masteries are implemented, there are very few highly specific situations where they are worthwhile, but for the vast vast majority of play, they belong on the scrap heap. The only times I even think about them now (and I'm pretty certain I'm in the top 1% of all UO bard skill users) are when I try to force myself to use them, other than that, they are a pain and not useful.
Now, the reduction in bard timers has been a boon that hasn't received enough praise. Provoke has always been my favorite skill (probably because I was using it daily long before discord was even introduced) and the reduction in timer is noticeable and highly useful. Discord can really keep up with the "all kill" command on my discord/tamer now against most monster situations. Sad thing is, this part of the change probably took about 5 minutes of development time and was basically arbitrary...at least it shows they listened to us about something.
But like Poo said, I pretty much play exactly the same way as before the masteries came out. That really should be considered a disappointment for the development team given that the most enthusiastic bard skill users, the ones that are always trying to fit bard skills into different templates, the ones that use them constantly on a daily basis, can find little to no use for the new masteries.