In general, any type of crossover is going to improve your performance, but the sound differences, I think, are minimal. The factors that really affect sound are cam, muffler, and pipe diameter.
There are two types of crossovers: H and X. H is a dual exhaust, like the one you have now, with a transverse connecting pipe after the transmission linking the two main exhaust pipes. An X crossover, actually routes the two exhaust flows into each other. I definitely noticed low end torque gains on my 67 camaro ss after installing a 2.5" H crossover, and expect the same, if not better, with the TTI X pipe on my challenger.
When all is said and done, the sound of the car is going to be a very personal thing. One thing you may want to do is search youtube for videos of cars with dynomax, flowmaster, magnaflow and see what you like. Personally, I don't want a ridiculously loud car; headers are going to be loud enough, thank you. And I want a fast launch (i.e. low end torque) more than I want top end horsepower, in my environment, there are not very many opportunities to redline. As with most things, you have to decide what you want out of the car. The best part is, you can change your mind later on.