I'm impressed with what Extra Boy can do for vocal removal. I've not tried it yet as any sort of effect; I don't expect to find anything too useful for my purposes, but I might be surprised. I've been called on to create "karaoke" versions of songs off and on the last several years for various reasons. For lack of any other choice, I'd always done the "invert one track and sum" approach and hated the results. With Extra Boy, I don't have to cringe at what I hand over any more.
GUI: It's fine. It's straight forward, and gets the job done. I'm not entirely sure it was worth spreading the controls over two tabs, but what the heck.
Sound: When using it for vocal removal, there are some artifacts left but they're minor and livable, especially after some tweaking of the controls, which let you tune the effect quite a bit. Meanwhile the sound of the music left behind is excellent.
Documentation: Needs some. Not a lot, but some. Right now there's not much info on what any control does. The sliders are mostly pretty obvious, but the buttons aren't always.
Presets: There are a number of buttons that give you different modes of operation, but I'm not sure I'd call them presets. It's adequate.
Customer Support: No idea. Haven't needed it. So, I put in a 7 but don't take it seriously. It may well ought to be a 10.
Value: It's grrrrrrreat! It's free and it works well. Not clear I have a need for the "Pro" version, but that appears to be priced reasonably. I may well make a donation for this one.
Stability: Seems fine. Haven't torture tested it, but it's not that kind of thing, now, is it.
I am a user. I expect a program to work on its own, and not have to be installed into another programs directory.If the program is ziped, as this one is, it should have auto extration. I would pay the $30.00 for the pro version if it came on a CD, or DVD, and extracted itself into its own directory and was stand alone, or a master module that came with the first module you ordered like Extra Boy, and of which the other models would automatically install into. As far as that is concerned, why not have all the programs you offer on one DVD, and have a license for each module to activatre that module?