IME, there are a lot of bass cabs out there with really cruddy tweeters, or with tweeters that were added haphazardly because it was the hot thing to do, but the manufacturer didn't spend the time to engineer the cab/crossover/drivers/etc properly. For such cabs, an attenuator is a blessing, that's for sure.
But, I have also found a number of brands which did do their homework, and which have very excellent sounding tweeters. I wholeheartedly join in the praise for Jim Bergantino's excellent incorporation of tweeters into (some of) his cabs. He chooses what he feels is the best tweeter for the job (and to the best of my knowledge, he uses at least two different tweets - one for small cabs, like HT112, and one for larger cabs, like HT210/HT115/HT310, etc.). Perhaps more importantly, he really does his homework on the crossover side of things, and achieves a great marriage of tweeter to driver(s). Certainly, Bergantino tweeters/crossovers are among the best in the business.
I am also quite fond of the silk dome tweeters used by Accugroove and ACME. The are very smooth, and extremely resistant to hiss. I often find myself boosting the highs a bit with these cabs, though, but they respond great to EQ, and the net effect is quite pleasant.
With regard to Jim's NV line, I think that you would be surprised by the amount of high end information that you can hear. The NV215, with its 6" midrange, is certainly the most upper mid & treble present of the group (and my personal favorite), but if you often play with overdrive/distortion, you may prefer the 610 or 425.
EA's Wizzy takes a unique approach by using a wizzer cone on its 12" driver. The Wizzy has great high range definition and articulation, but never sounds harsh. Of course, it's not well suited to a super sparkly tone, but I find that I can hear a good deal of upper midrange information. Steve Azola made some "Super Wizzy" 2x12's, which I was lucky enough to pick up. These suckers have it all going on, and all without tweeters!
But, in the end, there are good and bad choices in both camps. If you do decide to go with Bergantino, though, you really can't go wrong, whether you choose tweets or not.
Later, Tom.