I'm a coffee snob and home coffee roaster. I've never tried the kopi luwak but I've always meant to just to say that I did.
I don't have high expectations though, as Tom from Sweet Maria's (sweet marias is the place I buy unroasted coffee from, and I highly recommend checking out their web site if you want to learn more about coffee) has rated it as "trucker coffee" and not even remotely worth the hype. Obviously this guy is in the biz to make a buck like anyone else, but I've been buying from them for years and I've come to respect his opinion.
I have had something similar (and considerably cheaper) called "Jaku Bird" coffee, which I believe was from somewhere in south america (Brazil maybe?its been a few years). The birds supposedly selectively eat the ripest coffee cherries, and they are then harvested after they, um, pass through. I found it to be a good coffee, but not remarkable in comparison to other very good coffees from the region. I enjoyed it but didn't feel compelled to buy more.
If you like coffee, the best thing you can do to improve your experience is start homeroasting. Commercial roasters routinely sell you old burned mediocre quality beans. Not unlike BMC, they're more interested in consistency than offering truly excellent coffee.
As to putting coffee in beer, a lot of the flavor compounds that make different varieties of coffee unique from one another are highly volatile, and aren't going to survive in beer. As long as you're not using total crap, I think you're unlikely to see a significant difference from one variety to another, especially when adding to an already strong flavored beer. I didn't say NO difference, just not significant.
Edit: Forgot to add my recommendation, which is: enjoy the coffee as coffee. Let us know what you think of it, and put something cheaper in your beer.
