I have a pair of Aphex 9001 Aural Exciters and a BBE 702 module, plugin cards for the DBX 900 rack.
They do sound different from each other. Of the two I might go for the Aural Exciter first, but it's a hard call.
I think the key is to use them sparingly and not on an entire mix. Using them on a specific part like vocals or the drum buss or whatever can be cool. You can get stuff to stand out a little bit without having to bump up the volume.
They are neat little tools, but if you plan to buy one and slap it across the mix that is not the best use of it in my opinion.