I've heard that they're a little "wimpy" sounding, and that they lack the Euro and USA growl. Is that true? It could have just been the Genz Benz, but it didn't sound like it to me.
Perhaps a tad less gutsy than a Euro or USA, but
far from wimpy. And there is a significant price difference as well - you
are going to get better tone as you go up rungs on the Spector ladder, but the same goes for Warwick & Musicman too.
Less growl? Yes, a touch less, but the Euro & especially the USA models are downright famous for their growl, and a good deal of that comes from the USA 9-volt and 18-volt preamps, & to a slightly lesser degree, the Tonepump preamp found in the Euro. These preamps can be purchased separately & retrofitted to the lower end models, depending on the model's pickups.
As for the others you mentioned, I like the playability of the Ray34, but I own a Musicman Stingray, and it's hard to equal the bite & balls of the EBMM version. The Spector and Stingray sounds are different animals though.
And the Warwicks? Their tone is usually good, but I've just never played a 'Wick with a neck that felt right to me....
I suggest you ask this same question over in the Spector Club thread, and I'm sure owners of the Legend & Performer Series will chime in & give you their honest appraisals of these fine basses too.